int main(int argc, char *argv[])
{
  int rank = 0;
#ifdef HAVE_MPI
  // TODO: figure out the right thing to do here...
  // may want to modify argc and argv before we make the following call:
  Teuchos::GlobalMPISession mpiSession(&argc, &argv,0);
  rank=mpiSession.getRank();
#else
#endif
  bool useLineSearch = false;

  int pToAdd = 2; // for optimal test function approximation
  int pToAddForStreamFunction = 2;
  double nonlinearStepSize = 1.0;
  double dt = 0.5;
  double nonlinearRelativeEnergyTolerance = 0.015; // used to determine convergence of the nonlinear solution
  //  double nonlinearRelativeEnergyTolerance = 0.15; // used to determine convergence of the nonlinear solution
  double eps = 1.0/64.0; // width of ramp up to 1.0 for top BC;  eps == 0 ==> soln not in H1
  // epsilon above is chosen to match our initial 16x16 mesh, to avoid quadrature errors.
  //  double eps = 0.0; // John Evans's problem: not in H^1
  bool enforceLocalConservation = false;
  bool enforceOneIrregularity = true;
  bool reportPerCellErrors  = true;
  bool useMumps = true;

  int horizontalCells, verticalCells;

  int maxIters = 50; // for nonlinear steps

  vector<double> ReValues;

  // usage: polyOrder [numRefinements]
  // parse args:
  if (argc < 6)
  {
    cout << "Usage: NavierStokesCavityFlowContinuationFixedMesh fieldPolyOrder hCells vCells energyErrorGoal Re0 [Re1 ...]\n";
    return -1;
  }
  int polyOrder = atoi(argv[1]);
  horizontalCells = atoi(argv[2]);
  verticalCells = atoi(argv[3]);
  double energyErrorGoal = atof(argv[4]);
  for (int i=5; i<argc; i++)
  {
    ReValues.push_back(atof(argv[i]));
  }
  if (rank == 0)
  {
    cout << "L^2 order: " << polyOrder << endl;
    cout << "initial mesh size: " << horizontalCells << " x " << verticalCells << endl;
    cout << "energy error goal: " << energyErrorGoal << endl;
    cout << "Reynolds number values for continuation:\n";
    for (int i=0; i<ReValues.size(); i++)
    {
      cout << ReValues[i] << ", ";
    }
    cout << endl;
  }

  FieldContainer<double> quadPoints(4,2);

  quadPoints(0,0) = 0.0; // x1
  quadPoints(0,1) = 0.0; // y1
  quadPoints(1,0) = 1.0;
  quadPoints(1,1) = 0.0;
  quadPoints(2,0) = 1.0;
  quadPoints(2,1) = 1.0;
  quadPoints(3,0) = 0.0;
  quadPoints(3,1) = 1.0;

  // define meshes:
  int H1Order = polyOrder + 1;
  bool useTriangles = false;
  bool meshHasTriangles = useTriangles;

  double minL2Increment = 1e-8;

  // get variable definitions:
  VarFactory varFactory = VGPStokesFormulation::vgpVarFactory();
  u1 = varFactory.fieldVar(VGP_U1_S);
  u2 = varFactory.fieldVar(VGP_U2_S);
  sigma11 = varFactory.fieldVar(VGP_SIGMA11_S);
  sigma12 = varFactory.fieldVar(VGP_SIGMA12_S);
  sigma21 = varFactory.fieldVar(VGP_SIGMA21_S);
  sigma22 = varFactory.fieldVar(VGP_SIGMA22_S);
  p = varFactory.fieldVar(VGP_P_S);

  u1hat = varFactory.traceVar(VGP_U1HAT_S);
  u2hat = varFactory.traceVar(VGP_U2HAT_S);
  t1n = varFactory.fluxVar(VGP_T1HAT_S);
  t2n = varFactory.fluxVar(VGP_T2HAT_S);

  v1 = varFactory.testVar(VGP_V1_S, HGRAD);
  v2 = varFactory.testVar(VGP_V2_S, HGRAD);
  tau1 = varFactory.testVar(VGP_TAU1_S, HDIV);
  tau2 = varFactory.testVar(VGP_TAU2_S, HDIV);
  q = varFactory.testVar(VGP_Q_S, HGRAD);

  FunctionPtr u1_0 = Teuchos::rcp( new U1_0(eps) );
  FunctionPtr u2_0 = Teuchos::rcp( new U2_0 );
  FunctionPtr zero = Function::zero();
  ParameterFunctionPtr Re_param = ParameterFunction::parameterFunction(1);
  VGPNavierStokesProblem problem = VGPNavierStokesProblem(Re_param,quadPoints,
                                   horizontalCells,verticalCells,
                                   H1Order, pToAdd,
                                   u1_0, u2_0,  // BC for u
                                   zero, zero); // zero forcing function
  SolutionPtr solution = problem.backgroundFlow();
  SolutionPtr solnIncrement = problem.solutionIncrement();

  Teuchos::RCP<Mesh> mesh = problem.mesh();
  mesh->registerSolution(solution);
  mesh->registerSolution(solnIncrement);

  ///////////////////////////////////////////////////////////////////////////

  // define bilinear form for stream function:
  VarFactory streamVarFactory;
  VarPtr phi_hat = streamVarFactory.traceVar("\\widehat{\\phi}");
  VarPtr psin_hat = streamVarFactory.fluxVar("\\widehat{\\psi}_n");
  VarPtr psi_1 = streamVarFactory.fieldVar("\\psi_1");
  VarPtr psi_2 = streamVarFactory.fieldVar("\\psi_2");
  VarPtr phi = streamVarFactory.fieldVar("\\phi");
  VarPtr q_s = streamVarFactory.testVar("q_s", HGRAD);
  VarPtr v_s = streamVarFactory.testVar("v_s", HDIV);
  BFPtr streamBF = Teuchos::rcp( new BF(streamVarFactory) );
  streamBF->addTerm(psi_1, q_s->dx());
  streamBF->addTerm(psi_2, q_s->dy());
  streamBF->addTerm(-psin_hat, q_s);

  streamBF->addTerm(psi_1, v_s->x());
  streamBF->addTerm(psi_2, v_s->y());
  streamBF->addTerm(phi, v_s->div());
  streamBF->addTerm(-phi_hat, v_s->dot_normal());

  Teuchos::RCP<Mesh> streamMesh, overkillMesh;

  streamMesh = MeshFactory::buildQuadMesh(quadPoints, horizontalCells, verticalCells,
                                          streamBF, H1Order+pToAddForStreamFunction,
                                          H1Order+pToAdd+pToAddForStreamFunction, useTriangles);

  mesh->registerObserver(streamMesh); // will refine streamMesh in the same way as mesh.

  map<int, double> dofsToL2error; // key: numGlobalDofs, value: total L2error compared with overkill
  vector< VarPtr > fields;
  fields.push_back(u1);
  fields.push_back(u2);
  fields.push_back(sigma11);
  fields.push_back(sigma12);
  fields.push_back(sigma21);
  fields.push_back(sigma22);
  fields.push_back(p);

  if (rank == 0)
  {
    cout << "Starting mesh has " << horizontalCells << " x " << verticalCells << " elements and ";
    cout << mesh->numGlobalDofs() << " total dofs.\n";
    cout << "polyOrder = " << polyOrder << endl;
    cout << "pToAdd = " << pToAdd << endl;
    cout << "eps for top BC = " << eps << endl;

    if (useTriangles)
    {
      cout << "Using triangles.\n";
    }
    if (enforceLocalConservation)
    {
      cout << "Enforcing local conservation.\n";
    }
    else
    {
      cout << "NOT enforcing local conservation.\n";
    }
    if (enforceOneIrregularity)
    {
      cout << "Enforcing 1-irregularity.\n";
    }
    else
    {
      cout << "NOT enforcing 1-irregularity.\n";
    }
  }

  ////////////////////   CREATE BCs   ///////////////////////
  SpatialFilterPtr entireBoundary = Teuchos::rcp( new SpatialFilterUnfiltered );

  FunctionPtr u1_prev = Function::solution(u1,solution);
  FunctionPtr u2_prev = Function::solution(u2,solution);

  FunctionPtr u1hat_prev = Function::solution(u1hat,solution);
  FunctionPtr u2hat_prev = Function::solution(u2hat,solution);


  ////////////////////   SOLVE & REFINE   ///////////////////////

  FunctionPtr vorticity = Teuchos::rcp( new PreviousSolutionFunction(solution, - u1->dy() + u2->dx() ) );
  //  FunctionPtr vorticity = Teuchos::rcp( new PreviousSolutionFunction(solution,sigma12 - sigma21) );
  RHSPtr streamRHS = RHS::rhs();
  streamRHS->addTerm(vorticity * q_s);
  ((PreviousSolutionFunction*) vorticity.get())->setOverrideMeshCheck(true);
  ((PreviousSolutionFunction*) u1_prev.get())->setOverrideMeshCheck(true);
  ((PreviousSolutionFunction*) u2_prev.get())->setOverrideMeshCheck(true);

  BCPtr streamBC = BC::bc();
  //  streamBC->addDirichlet(psin_hat, entireBoundary, u0_cross_n);
  streamBC->addDirichlet(phi_hat, entireBoundary, zero);
  //  streamBC->addZeroMeanConstraint(phi);

  IPPtr streamIP = Teuchos::rcp( new IP );
  streamIP->addTerm(q_s);
  streamIP->addTerm(q_s->grad());
  streamIP->addTerm(v_s);
  streamIP->addTerm(v_s->div());
  SolutionPtr streamSolution = Teuchos::rcp( new Solution( streamMesh, streamBC, streamRHS, streamIP ) );

  if (enforceLocalConservation)
  {
    FunctionPtr zero = Function::zero();
    solution->lagrangeConstraints()->addConstraint(u1hat->times_normal_x() + u2hat->times_normal_y()==zero);
    solnIncrement->lagrangeConstraints()->addConstraint(u1hat->times_normal_x() + u2hat->times_normal_y()==zero);
  }

  if (true)
  {
    FunctionPtr u1_incr = Function::solution(u1, solnIncrement);
    FunctionPtr u2_incr = Function::solution(u2, solnIncrement);
    FunctionPtr sigma11_incr = Function::solution(sigma11, solnIncrement);
    FunctionPtr sigma12_incr = Function::solution(sigma12, solnIncrement);
    FunctionPtr sigma21_incr = Function::solution(sigma21, solnIncrement);
    FunctionPtr sigma22_incr = Function::solution(sigma22, solnIncrement);
    FunctionPtr p_incr = Function::solution(p, solnIncrement);

    FunctionPtr l2_incr = u1_incr * u1_incr + u2_incr * u2_incr + p_incr * p_incr
                          + sigma11_incr * sigma11_incr + sigma12_incr * sigma12_incr
                          + sigma21_incr * sigma21_incr + sigma22_incr * sigma22_incr;

    double energyThreshold = 0.20;
    Teuchos::RCP< RefinementStrategy > refinementStrategy = Teuchos::rcp( new RefinementStrategy( solnIncrement, energyThreshold ));

    for (int i=0; i<ReValues.size(); i++)
    {
      double Re = ReValues[i];
      Re_param->setValue(Re);
      if (rank==0) cout << "Solving with Re = " << Re << ":\n";
      double energyErrorTotal;
      do
      {
        double incr_norm;
        do
        {
          problem.iterate(useLineSearch);
          incr_norm = sqrt(l2_incr->integrate(problem.mesh()));
          if (rank==0)
          {
            cout << "\x1B[2K"; // Erase the entire current line.
            cout << "\x1B[0E"; // Move to the beginning of the current line.
            cout << "Iteration: " << problem.iterationCount() << "; L^2(incr) = " << incr_norm;
            flush(cout);
          }
        }
        while ((incr_norm > minL2Increment ) && (problem.iterationCount() < maxIters));
        if (rank==0) cout << endl;
        problem.setIterationCount(1); // 1 means reuse background flow (which we must, given that we want continuation in Re...)
        energyErrorTotal = solnIncrement->energyErrorTotal(); //solution->energyErrorTotal();
        if (energyErrorTotal > energyErrorGoal)
        {
          refinementStrategy->refine(false);
        }
        if (rank==0)
        {
          cout << "Energy error: " << energyErrorTotal << endl;
        }
      }
      while (energyErrorTotal > energyErrorGoal);
    }
  }

  double energyErrorTotal = solution->energyErrorTotal();
  double incrementalEnergyErrorTotal = solnIncrement->energyErrorTotal();
  if (rank == 0)
  {
    cout << "final mesh has " << mesh->numActiveElements() << " elements and " << mesh->numGlobalDofs() << " dofs.\n";
    cout << "energy error: " << energyErrorTotal << endl;
    cout << "  (Incremental solution's energy error is " << incrementalEnergyErrorTotal << ".)\n";
  }

  FunctionPtr u1_sq = u1_prev * u1_prev;
  FunctionPtr u_dot_u = u1_sq + (u2_prev * u2_prev);
  FunctionPtr u_mag = Teuchos::rcp( new SqrtFunction( u_dot_u ) );
  FunctionPtr u_div = Teuchos::rcp( new PreviousSolutionFunction(solution, u1->dx() + u2->dy() ) );
  FunctionPtr massFlux = Teuchos::rcp( new PreviousSolutionFunction(solution, u1hat->times_normal_x() + u2hat->times_normal_y()) );

  // check that the zero mean pressure is being correctly imposed:
  FunctionPtr p_prev = Teuchos::rcp( new PreviousSolutionFunction(solution,p) );
  double p_avg = p_prev->integrate(mesh);
  if (rank==0)
    cout << "Integral of pressure: " << p_avg << endl;

  // integrate massFlux over each element (a test):
  // fake a new bilinear form so we can integrate against 1
  VarPtr testOne = varFactory.testVar("1",CONSTANT_SCALAR);
  BFPtr fakeBF = Teuchos::rcp( new BF(varFactory) );
  LinearTermPtr massFluxTerm = massFlux * testOne;

  CellTopoPtrLegacy quadTopoPtr = Teuchos::rcp(new shards::CellTopology(shards::getCellTopologyData<shards::Quadrilateral<4> >() ));
  DofOrderingFactory dofOrderingFactory(fakeBF);
  int fakeTestOrder = H1Order;
  DofOrderingPtr testOrdering = dofOrderingFactory.testOrdering(fakeTestOrder, *quadTopoPtr);

  int testOneIndex = testOrdering->getDofIndex(testOne->ID(),0);
  vector< ElementTypePtr > elemTypes = mesh->elementTypes(); // global element types
  map<int, double> massFluxIntegral; // cellID -> integral
  double maxMassFluxIntegral = 0.0;
  double totalMassFlux = 0.0;
  double totalAbsMassFlux = 0.0;
  double maxCellMeasure = 0;
  double minCellMeasure = 1;
  for (vector< ElementTypePtr >::iterator elemTypeIt = elemTypes.begin(); elemTypeIt != elemTypes.end(); elemTypeIt++)
  {
    ElementTypePtr elemType = *elemTypeIt;
    vector< ElementPtr > elems = mesh->elementsOfTypeGlobal(elemType);
    vector<GlobalIndexType> cellIDs;
    for (int i=0; i<elems.size(); i++)
    {
      cellIDs.push_back(elems[i]->cellID());
    }
    FieldContainer<double> physicalCellNodes = mesh->physicalCellNodesGlobal(elemType);
    BasisCachePtr basisCache = Teuchos::rcp( new BasisCache(elemType,mesh,polyOrder) ); // enrich by trial space order
    basisCache->setPhysicalCellNodes(physicalCellNodes,cellIDs,true); // true: create side caches
    FieldContainer<double> cellMeasures = basisCache->getCellMeasures();
    FieldContainer<double> fakeRHSIntegrals(elems.size(),testOrdering->totalDofs());
    massFluxTerm->integrate(fakeRHSIntegrals,testOrdering,basisCache,true); // true: force side evaluation
    //      cout << "fakeRHSIntegrals:\n" << fakeRHSIntegrals;
    for (int i=0; i<elems.size(); i++)
    {
      int cellID = cellIDs[i];
      // pick out the ones for testOne:
      massFluxIntegral[cellID] = fakeRHSIntegrals(i,testOneIndex);
    }
    // find the largest:
    for (int i=0; i<elems.size(); i++)
    {
      int cellID = cellIDs[i];
      maxMassFluxIntegral = max(abs(massFluxIntegral[cellID]), maxMassFluxIntegral);
    }
    for (int i=0; i<elems.size(); i++)
    {
      int cellID = cellIDs[i];
      maxCellMeasure = max(maxCellMeasure,cellMeasures(i));
      minCellMeasure = min(minCellMeasure,cellMeasures(i));
      maxMassFluxIntegral = max(abs(massFluxIntegral[cellID]), maxMassFluxIntegral);
      totalMassFlux += massFluxIntegral[cellID];
      totalAbsMassFlux += abs( massFluxIntegral[cellID] );
    }
  }
  if (rank==0)
  {
    cout << "largest mass flux: " << maxMassFluxIntegral << endl;
    cout << "total mass flux: " << totalMassFlux << endl;
    cout << "sum of mass flux absolute value: " << totalAbsMassFlux << endl;
    cout << "largest h: " << sqrt(maxCellMeasure) << endl;
    cout << "smallest h: " << sqrt(minCellMeasure) << endl;
    cout << "ratio of largest / smallest h: " << sqrt(maxCellMeasure) / sqrt(minCellMeasure) << endl;
  }
  if (rank == 0)
  {
    cout << "phi ID: " << phi->ID() << endl;
    cout << "psi1 ID: " << psi_1->ID() << endl;
    cout << "psi2 ID: " << psi_2->ID() << endl;

    cout << "streamMesh has " << streamMesh->numActiveElements() << " elements.\n";
    cout << "solving for approximate stream function...\n";
  }

  streamSolution->solve(useMumps);
  energyErrorTotal = streamSolution->energyErrorTotal();
  if (rank == 0)
  {
    cout << "...solved.\n";
    cout << "Stream mesh has energy error: " << energyErrorTotal << endl;
  }

  if (rank==0)
  {
    solution->writeToVTK("nsCavitySoln.vtk");
    if (! meshHasTriangles )
    {
      massFlux->writeBoundaryValuesToMATLABFile(solution->mesh(), "massFlux.dat");
      u_mag->writeValuesToMATLABFile(solution->mesh(), "u_mag.m");
      u_div->writeValuesToMATLABFile(solution->mesh(), "u_div.m");
      solution->writeFieldsToFile(u1->ID(), "u1.m");
      solution->writeFluxesToFile(u1hat->ID(), "u1_hat.dat");
      solution->writeFieldsToFile(u2->ID(), "u2.m");
      solution->writeFluxesToFile(u2hat->ID(), "u2_hat.dat");
      solution->writeFieldsToFile(p->ID(), "p.m");
      streamSolution->writeFieldsToFile(phi->ID(), "phi.m");

      streamSolution->writeFluxesToFile(phi_hat->ID(), "phi_hat.dat");
      streamSolution->writeFieldsToFile(psi_1->ID(), "psi1.m");
      streamSolution->writeFieldsToFile(psi_2->ID(), "psi2.m");
      vorticity->writeValuesToMATLABFile(streamMesh, "vorticity.m");

      FunctionPtr ten = Teuchos::rcp( new ConstantScalarFunction(10) );
      ten->writeBoundaryValuesToMATLABFile(solution->mesh(), "skeleton.dat");
      cout << "wrote files: u_mag.m, u_div.m, u1.m, u1_hat.dat, u2.m, u2_hat.dat, p.m, phi.m, vorticity.m.\n";
    }
    else
    {
      solution->writeToFile(u1->ID(), "u1.dat");
      solution->writeToFile(u2->ID(), "u2.dat");
      solution->writeToFile(u2->ID(), "p.dat");
      cout << "wrote files: u1.dat, u2.dat, p.dat\n";
    }

    FieldContainer<double> points = pointGrid(0, 1, 0, 1, 100);
    FieldContainer<double> pointData = solutionData(points, streamSolution, phi);
    GnuPlotUtil::writeXYPoints("phi_patch_navierStokes_cavity.dat", pointData);
    set<double> patchContourLevels = diagonalContourLevels(pointData,1);
    vector<string> patchDataPath;
    patchDataPath.push_back("phi_patch_navierStokes_cavity.dat");
    GnuPlotUtil::writeContourPlotScript(patchContourLevels, patchDataPath, "lidCavityNavierStokes.p");

    GnuPlotUtil::writeExactMeshSkeleton("lid_navierStokes_continuation_adaptive", mesh, 2);

    writePatchValues(0, 1, 0, 1, streamSolution, phi, "phi_patch.m");
    writePatchValues(0, .1, 0, .1, streamSolution, phi, "phi_patch_detail.m");
    writePatchValues(0, .01, 0, .01, streamSolution, phi, "phi_patch_minute_detail.m");
    writePatchValues(0, .001, 0, .001, streamSolution, phi, "phi_patch_minute_minute_detail.m");
  }

  return 0;
}
bool HConvergenceStudyTests::testBestApproximationErrorComputation() {
  bool success = true;

  bool enrichVelocity = false; // true would be for the "compliant" norm, which isn't working well yet
  
  int minLogElements = 0, maxLogElements = minLogElements;
  int numCells1D = pow(2.0,minLogElements);
  int H1Order = 1;
  int pToAdd = 2;
  
  double tol = 1e-16;
  double Re = 40.0;
  
  VarFactory varFactory = VGPStokesFormulation::vgpVarFactory();
  VarPtr u1_vgp = varFactory.fieldVar(VGP_U1_S);
  VarPtr u2_vgp = varFactory.fieldVar(VGP_U2_S);
  VarPtr sigma11_vgp = varFactory.fieldVar(VGP_SIGMA11_S);
  VarPtr sigma12_vgp = varFactory.fieldVar(VGP_SIGMA12_S);
  VarPtr sigma21_vgp = varFactory.fieldVar(VGP_SIGMA21_S);
  VarPtr sigma22_vgp = varFactory.fieldVar(VGP_SIGMA22_S);
  VarPtr p_vgp = varFactory.fieldVar(VGP_P_S);
  
  VGPStokesFormulation stokesForm(1/Re);
  
  int numCellsFineMesh = 20; // for computing a zero-mean pressure
  int H1OrderFineMesh = 5;
  
  // define Kovasznay domain:
  FieldContainer<double> quadPointsKovasznay(4,2);
  
  // Domain from Evans Hughes for Navier-Stokes:
  quadPointsKovasznay(0,0) =  0.0; // x1
  quadPointsKovasznay(0,1) = -0.5; // y1
  quadPointsKovasznay(1,0) =  1.0;
  quadPointsKovasznay(1,1) = -0.5;
  quadPointsKovasznay(2,0) =  1.0;
  quadPointsKovasznay(2,1) =  0.5;
  quadPointsKovasznay(3,0) =  0.0;
  quadPointsKovasznay(3,1) =  0.5;
  
  FunctionPtr zero = Function::zero();
  bool dontEnhanceFluxes = false;
  VGPNavierStokesProblem zeroProblem = VGPNavierStokesProblem(Re, quadPointsKovasznay,
                                                              numCellsFineMesh, numCellsFineMesh,
                                                              H1OrderFineMesh, pToAdd,
                                                              zero, zero, zero, enrichVelocity, dontEnhanceFluxes);
  
  FunctionPtr u1_exact, u2_exact, p_exact;
  NavierStokesFormulation::setKovasznay(Re, zeroProblem.mesh(), u1_exact, u2_exact, p_exact);
  
  
  VGPNavierStokesProblem problem = VGPNavierStokesProblem(Re,quadPointsKovasznay,
                                                          numCells1D,numCells1D,
                                                          H1Order, pToAdd,
                                                          u1_exact, u2_exact, p_exact, enrichVelocity, dontEnhanceFluxes);

  HConvergenceStudy study(problem.exactSolution(),
                          problem.mesh()->bilinearForm(),
                          problem.exactSolution()->rhs(),
                          problem.backgroundFlow()->bc(),
                          problem.bf()->graphNorm(),
                          minLogElements, maxLogElements,
                          H1Order, pToAdd, false, false, false);
  study.setReportRelativeErrors(false); // we want absolute errors

  Teuchos::RCP<Mesh> mesh = problem.mesh();
  
  int cubatureDegreeEnrichment = 10;
  
  int L2Order = H1Order - 1;
  int meshCubatureDegree = L2Order + H1Order + pToAdd;

  study.setCubatureDegreeForExact(cubatureDegreeEnrichment + meshCubatureDegree);
  
  FunctionPtr f = u1_exact;
  int trialID = u1_vgp->ID();
  {
    double fIntegral = f->integrate(mesh,cubatureDegreeEnrichment);
//    cout << "testBestApproximationErrorComputation: integral of f on whole mesh = " << fIntegral << endl;
    
    double l2ErrorOfAverage = (Function::constant(fIntegral) - f)->l2norm(mesh,cubatureDegreeEnrichment);
//    cout << "testBestApproximationErrorComputation: l2 error of fIntegral: " << l2ErrorOfAverage << endl;
    
    ElementTypePtr elemType = mesh->elementTypes()[0];
    vector<GlobalIndexType> cellIDs = mesh->cellIDsOfTypeGlobal(elemType);
    
    bool testVsTest = false;
    BasisCachePtr basisCache = Teuchos::rcp( new BasisCache(elemType, mesh, testVsTest, cubatureDegreeEnrichment) );
    basisCache->setPhysicalCellNodes(mesh->physicalCellNodesGlobal(elemType), cellIDs, false); // false: no side cache

    FieldContainer<double> projectionValues(cellIDs.size());
    f->integrate(projectionValues, basisCache);
    FieldContainer<double> cellMeasures = basisCache->getCellMeasures();
    
    for (int i=0; i<projectionValues.size(); i++) {
      projectionValues(i) /= cellMeasures(i);
    }
    
    // since we're not worried about the actual solution values at all, just use a single zero solution:
    vector< SolutionPtr > solutions;
    solutions.push_back( problem.backgroundFlow() );
    
    study.setSolutions(solutions); // this will call computeError()
    
    
    double approximationError = study.bestApproximationErrors()[trialID][0]; // 0: solution/mesh index
    
    // for a single-cell mesh, approximation error should be the same as the L^2 error of the average
    double diff = abs(approximationError - l2ErrorOfAverage);
  
    if (diff > tol) {
      cout << "testBestApproximationErrorComputation: diff " << diff << " exceeds tol " << tol << endl;
      success = false;
    } else {
//      cout << "testBestApproximationErrorComputation: diff " << diff << " is below tol " << tol << endl;
    }
  }
  return success;
}
Beispiel #3
0
int main(int argc, char *argv[]) {
  // Process command line arguments
  if (argc > 1)
    numRefs = atof(argv[1]);
#ifdef HAVE_MPI
  Teuchos::GlobalMPISession mpiSession(&argc, &argv,0);
  int rank=mpiSession.getRank();
  int numProcs=mpiSession.getNProc();
#else
  int rank = 0;
  int numProcs = 1;
#endif

  FunctionPtr beta = Teuchos::rcp(new Beta());

  ////////////////////////////////////////////////////////////////////
  // DEFINE VARIABLES 
  ////////////////////////////////////////////////////////////////////
  // test variables
  VarFactory varFactory; 
  VarPtr tau = varFactory.testVar("\\tau", HDIV);
  VarPtr v = varFactory.testVar("v", HGRAD);

  // trial variables
  VarPtr uhat = varFactory.traceVar("\\widehat{u}");
  VarPtr beta_n_u_minus_sigma_n = varFactory.fluxVar("\\widehat{\\beta \\cdot n u - \\sigma_{n}}");
  VarPtr u = varFactory.fieldVar("u");
  VarPtr sigma1 = varFactory.fieldVar("\\sigma_1");
  VarPtr sigma2 = varFactory.fieldVar("\\sigma_2");

  ////////////////////////////////////////////////////////////////////
  // CREATE MESH 
  ////////////////////////////////////////////////////////////////////

  BFPtr confusionBF = Teuchos::rcp( new BF(varFactory) );

  FieldContainer<double> meshBoundary(4,2);

  meshBoundary(0,0) =  0.0; // x1
  meshBoundary(0,1) = -2.0; // y1
  meshBoundary(1,0) =  4.0;
  meshBoundary(1,1) = -2.0;
  meshBoundary(2,0) =  4.0;
  meshBoundary(2,1) =  2.0;
  meshBoundary(3,0) =  0.0;
  meshBoundary(3,1) =  2.0;

  int horizontalCells = 4, verticalCells = 4;

  // create a pointer to a new mesh:
  Teuchos::RCP<Mesh> mesh = Mesh::buildQuadMesh(meshBoundary, horizontalCells, verticalCells,
      confusionBF, H1Order, H1Order+pToAdd, false);

  ////////////////////////////////////////////////////////////////////
  // INITIALIZE BACKGROUND FLOW FUNCTIONS
  ////////////////////////////////////////////////////////////////////

  BCPtr nullBC = Teuchos::rcp((BC*)NULL);
  RHSPtr nullRHS = Teuchos::rcp((RHS*)NULL);
  IPPtr nullIP = Teuchos::rcp((IP*)NULL);
  SolutionPtr prevTimeFlow = Teuchos::rcp(new Solution(mesh, nullBC, nullRHS, nullIP) );  
  SolutionPtr flowResidual = Teuchos::rcp(new Solution(mesh, nullBC, nullRHS, nullIP) );  

  FunctionPtr u_prev_time = Teuchos::rcp( new PreviousSolutionFunction(prevTimeFlow, u) );

  // ==================== SET INITIAL GUESS ==========================
  double u_free = 0.0;
  double sigma1_free = 0.0;
  double sigma2_free = 0.0;
  map<int, Teuchos::RCP<Function> > functionMap;
  functionMap[u->ID()] = Teuchos::rcp( new ConstantScalarFunction(u_free) );
  functionMap[sigma1->ID()] = Teuchos::rcp( new ConstantScalarFunction(sigma1_free) );
  functionMap[sigma2->ID()] = Teuchos::rcp( new ConstantScalarFunction(sigma2_free) );

  prevTimeFlow->projectOntoMesh(functionMap);
  // ==================== END SET INITIAL GUESS ==========================

  ////////////////////////////////////////////////////////////////////
  // DEFINE BILINEAR FORM
  ////////////////////////////////////////////////////////////////////

  // tau terms:
  confusionBF->addTerm(sigma1 / epsilon, tau->x());
  confusionBF->addTerm(sigma2 / epsilon, tau->y());
  confusionBF->addTerm(u, tau->div());
  confusionBF->addTerm(-uhat, tau->dot_normal());

  // v terms:
  confusionBF->addTerm( sigma1, v->dx() );
  confusionBF->addTerm( sigma2, v->dy() );
  confusionBF->addTerm( beta * u, - v->grad() );
  confusionBF->addTerm( beta_n_u_minus_sigma_n, v);

  ////////////////////////////////////////////////////////////////////
  // TIMESTEPPING TERMS
  ////////////////////////////////////////////////////////////////////
  Teuchos::RCP<RHSEasy> rhs = Teuchos::rcp( new RHSEasy );

  double dt = 0.25;
  FunctionPtr invDt = Teuchos::rcp(new ScalarParamFunction(1.0/dt));    
  if (rank==0){
    cout << "Timestep dt = " << dt << endl;
  }
  if (transient)
  {
    confusionBF->addTerm( u, invDt*v );
    rhs->addTerm( u_prev_time * invDt * v );
  }

  ////////////////////////////////////////////////////////////////////
  // DEFINE INNER PRODUCT
  ////////////////////////////////////////////////////////////////////

  // mathematician's norm
  IPPtr mathIP = Teuchos::rcp(new IP());
  mathIP->addTerm(tau);
  mathIP->addTerm(tau->div());

  mathIP->addTerm(v);
  mathIP->addTerm(v->grad());

  // quasi-optimal norm
  IPPtr qoptIP = Teuchos::rcp(new IP);
  qoptIP->addTerm( v );
  qoptIP->addTerm( tau / epsilon + v->grad() );
  qoptIP->addTerm( beta * v->grad() - tau->div() );

  // robust test norm
  IPPtr robIP = Teuchos::rcp(new IP);
  FunctionPtr ip_scaling = Teuchos::rcp( new EpsilonScaling(epsilon) ); 
  if (!enforceLocalConservation)
  {
    robIP->addTerm( ip_scaling * v );
    if (transient)
      robIP->addTerm( invDt * v );
  }
  robIP->addTerm( sqrt(epsilon) * v->grad() );
  // Weight these two terms for inflow
  FunctionPtr ip_weight = Teuchos::rcp( new IPWeight() );
  robIP->addTerm( ip_weight * beta * v->grad() );
  robIP->addTerm( ip_weight * tau->div() );
  robIP->addTerm( ip_scaling/sqrt(epsilon) * tau );
  if (enforceLocalConservation)
    robIP->addZeroMeanTerm( v );

  ////////////////////////////////////////////////////////////////////
  // DEFINE RHS
  ////////////////////////////////////////////////////////////////////

  FunctionPtr f = Teuchos::rcp( new ConstantScalarFunction(0.0) );
  rhs->addTerm( f * v ); // obviously, with f = 0 adding this term is not necessary!

  ////////////////////////////////////////////////////////////////////
  // DEFINE BC
  ////////////////////////////////////////////////////////////////////

  Teuchos::RCP<BCEasy> bc = Teuchos::rcp( new BCEasy );
  // Teuchos::RCP<PenaltyConstraints> pc = Teuchos::rcp( new PenaltyConstraints );
  SpatialFilterPtr lBoundary = Teuchos::rcp( new LeftBoundary );
  SpatialFilterPtr tbBoundary = Teuchos::rcp( new TopBottomBoundary );
  SpatialFilterPtr rBoundary = Teuchos::rcp( new RightBoundary );
  FunctionPtr u0 = Teuchos::rcp( new ZeroBC );
  FunctionPtr u_inlet = Teuchos::rcp( new InletBC );
  // FunctionPtr n = Teuchos::rcp( new UnitNormalFunction );
  bc->addDirichlet(beta_n_u_minus_sigma_n, lBoundary, u_inlet);
  bc->addDirichlet(beta_n_u_minus_sigma_n, tbBoundary, u0);
  bc->addDirichlet(uhat, rBoundary, u0);
  // pc->addConstraint(beta_n_u_minus_sigma_n - uhat == u0, rBoundary);

  ////////////////////////////////////////////////////////////////////
  // CREATE SOLUTION OBJECT
  ////////////////////////////////////////////////////////////////////
  Teuchos::RCP<Solution> solution = Teuchos::rcp( new Solution(mesh, bc, rhs, robIP) );
  // solution->setFilter(pc);

  // ==================== Enforce Local Conservation ==================
  if (enforceLocalConservation) {
    if (transient)
    {
      FunctionPtr conserved_rhs = u_prev_time * invDt;
      LinearTermPtr conserved_quantity = invDt * u;
      LinearTermPtr flux_part = Teuchos::rcp(new LinearTerm(-1.0, beta_n_u_minus_sigma_n));
      conserved_quantity->addTerm(flux_part, true);
      // conserved_quantity = conserved_quantity - beta_n_u_minus_sigma_n;
      solution->lagrangeConstraints()->addConstraint(conserved_quantity == conserved_rhs);
    }
    else
    {
      FunctionPtr zero = Teuchos::rcp( new ConstantScalarFunction(0.0) );
      solution->lagrangeConstraints()->addConstraint(beta_n_u_minus_sigma_n == zero);
    }
  }

  // ==================== Register Solutions ==========================
  mesh->registerSolution(solution);
  mesh->registerSolution(prevTimeFlow); // u_t(i-1)
  mesh->registerSolution(flowResidual); // u_t(i-1)

  double energyThreshold = 0.25; // for mesh refinements
  Teuchos::RCP<RefinementStrategy> refinementStrategy;
  refinementStrategy = Teuchos::rcp(new RefinementStrategy(solution,energyThreshold));

  ////////////////////////////////////////////////////////////////////
  // PSEUDO-TIME SOLVE STRATEGY 
  ////////////////////////////////////////////////////////////////////

  double time_tol = 1e-8;
  for (int refIndex=0; refIndex<=numRefs; refIndex++)
  {
    double L2_time_residual = 1e7;
    int timestepCount = 0;
    if (!transient)
      numTimeSteps = 1;
    while((L2_time_residual > time_tol) && (timestepCount < numTimeSteps))
    {
      solution->solve(false);
      // subtract solutions to get residual
      flowResidual->setSolution(solution); // reset previous time solution to current time sol
      flowResidual->addSolution(prevTimeFlow, -1.0);       
      double L2u = flowResidual->L2NormOfSolutionGlobal(u->ID());
      double L2sigma1 = flowResidual->L2NormOfSolutionGlobal(sigma1->ID());
      double L2sigma2 = flowResidual->L2NormOfSolutionGlobal(sigma2->ID());
      L2_time_residual = sqrt(L2u*L2u + L2sigma1*L2sigma1 + L2sigma2*L2sigma2);
      cout << endl << "Timestep: " << timestepCount << ", dt = " << dt << ", Time residual = " << L2_time_residual << endl;    	

      if (rank == 0)
      {
        stringstream outfile;
        if (transient)
          outfile << "TransientConfusion_" << refIndex << "_" << timestepCount;
        else
          outfile << "TransientConfusion_" << refIndex;
        solution->writeToVTK(outfile.str(), 5);
      }

      //////////////////////////////////////////////////////////////////////////
      // Check conservation by testing against one
      //////////////////////////////////////////////////////////////////////////
      VarPtr testOne = varFactory.testVar("1", CONSTANT_SCALAR);
      // Create a fake bilinear form for the testing
      BFPtr fakeBF = Teuchos::rcp( new BF(varFactory) );
      // Define our mass flux
      FunctionPtr flux_current_time = Teuchos::rcp( new PreviousSolutionFunction(solution, beta_n_u_minus_sigma_n) );
      FunctionPtr delta_u = Teuchos::rcp( new PreviousSolutionFunction(flowResidual, u) );
      LinearTermPtr surfaceFlux = -1.0 * flux_current_time * testOne;
      LinearTermPtr volumeChange = invDt * delta_u * testOne;
      LinearTermPtr massFluxTerm;
      if (transient)
      {
        massFluxTerm = volumeChange;
        // massFluxTerm->addTerm(surfaceFlux);
      }
      else
      {
        massFluxTerm = surfaceFlux;
      }
      // cout << "surface case = " << surfaceFlux->summands()[0].first->boundaryValueOnly() << " volume case = " << volumeChange->summands()[0].first->boundaryValueOnly() << endl;

      // FunctionPtr massFlux= Teuchos::rcp( new PreviousSolutionFunction(solution, beta_n_u_minus_sigma_n) );
      // LinearTermPtr massFluxTerm = massFlux * testOne;

      Teuchos::RCP<shards::CellTopology> quadTopoPtr = Teuchos::rcp(new shards::CellTopology(shards::getCellTopologyData<shards::Quadrilateral<4> >() ));
      DofOrderingFactory dofOrderingFactory(fakeBF);
      int fakeTestOrder = H1Order;
      DofOrderingPtr testOrdering = dofOrderingFactory.testOrdering(fakeTestOrder, *quadTopoPtr);

      int testOneIndex = testOrdering->getDofIndex(testOne->ID(),0);
      vector< ElementTypePtr > elemTypes = mesh->elementTypes(); // global element types
      map<int, double> massFluxIntegral; // cellID -> integral
      double maxMassFluxIntegral = 0.0;
      double totalMassFlux = 0.0;
      double totalAbsMassFlux = 0.0;
      for (vector< ElementTypePtr >::iterator elemTypeIt = elemTypes.begin(); elemTypeIt != elemTypes.end(); elemTypeIt++) 
      {
        ElementTypePtr elemType = *elemTypeIt;
        vector< ElementPtr > elems = mesh->elementsOfTypeGlobal(elemType);
        vector<int> cellIDs;
        for (int i=0; i<elems.size(); i++) {
          cellIDs.push_back(elems[i]->cellID());
        }
        FieldContainer<double> physicalCellNodes = mesh->physicalCellNodesGlobal(elemType);
        BasisCachePtr basisCache = Teuchos::rcp( new BasisCache(elemType,mesh) );
        basisCache->setPhysicalCellNodes(physicalCellNodes,cellIDs,true); // true: create side caches
        FieldContainer<double> cellMeasures = basisCache->getCellMeasures();
        FieldContainer<double> fakeRHSIntegrals(elems.size(),testOrdering->totalDofs());
        massFluxTerm->integrate(fakeRHSIntegrals,testOrdering,basisCache,true); // true: force side evaluation
        for (int i=0; i<elems.size(); i++) {
          int cellID = cellIDs[i];
          // pick out the ones for testOne:
          massFluxIntegral[cellID] = fakeRHSIntegrals(i,testOneIndex);
        }
        // find the largest:
        for (int i=0; i<elems.size(); i++) {
          int cellID = cellIDs[i];
          maxMassFluxIntegral = max(abs(massFluxIntegral[cellID]), maxMassFluxIntegral);
        }
        for (int i=0; i<elems.size(); i++) {
          int cellID = cellIDs[i];
          maxMassFluxIntegral = max(abs(massFluxIntegral[cellID]), maxMassFluxIntegral);
          totalMassFlux += massFluxIntegral[cellID];
          totalAbsMassFlux += abs( massFluxIntegral[cellID] );
        }
      }

      // Print results from processor with rank 0
      if (rank == 0)
      {
        cout << "largest mass flux: " << maxMassFluxIntegral << endl;
        cout << "total mass flux: " << totalMassFlux << endl;
        cout << "sum of mass flux absolute value: " << totalAbsMassFlux << endl;
      }

      prevTimeFlow->setSolution(solution); // reset previous time solution to current time sol
      timestepCount++;
    }

    if (refIndex < numRefs){
      if (rank==0){
        cout << "Performing refinement number " << refIndex << endl;
      }     
      refinementStrategy->refine(rank==0);    
      // RESET solution every refinement - make sure discretization error doesn't creep in
      // prevTimeFlow->projectOntoMesh(functionMap);
    }
  }

  return 0;
}
int main(int argc, char *argv[])
{
#ifdef HAVE_MPI
  Teuchos::GlobalMPISession mpiSession(&argc, &argv,0);
  int rank=mpiSession.getRank();
  int numProcs=mpiSession.getNProc();
#else
  int rank = 0;
  int numProcs = 1;
#endif
  int polyOrder = 3;
  int pToAdd = 2; // for tests

  // define our manufactured solution or problem bilinear form:
  bool useTriangles = false;

  FieldContainer<double> meshPoints(4,2);

  meshPoints(0,0) = 0.0; // x1
  meshPoints(0,1) = 0.0; // y1
  meshPoints(1,0) = 1.0;
  meshPoints(1,1) = 0.0;
  meshPoints(2,0) = 1.0;
  meshPoints(2,1) = 1.0;
  meshPoints(3,0) = 0.0;
  meshPoints(3,1) = 1.0;

  int H1Order = polyOrder + 1;
  int horizontalCells = 4, verticalCells = 4;

  double energyThreshold = 0.2; // for mesh refinements
  double nonlinearStepSize = 0.5;
  double nonlinearRelativeEnergyTolerance = 1e-8; // used to determine convergence of the nonlinear solution

  ////////////////////////////////////////////////////////////////////
  // DEFINE VARIABLES
  ////////////////////////////////////////////////////////////////////

  // new-style bilinear form definition
  VarFactory varFactory;
  VarPtr fhat = varFactory.fluxVar("\\widehat{f}");
  VarPtr u = varFactory.fieldVar("u");

  VarPtr v = varFactory.testVar("v",HGRAD);
  BFPtr bf = Teuchos::rcp( new BF(varFactory) ); // initialize bilinear form

  ////////////////////////////////////////////////////////////////////
  // CREATE MESH
  ////////////////////////////////////////////////////////////////////

  // create a pointer to a new mesh:
  Teuchos::RCP<Mesh> mesh = Mesh::buildQuadMesh(meshPoints, horizontalCells,
                            verticalCells, bf, H1Order,
                            H1Order+pToAdd, useTriangles);
  mesh->setPartitionPolicy(Teuchos::rcp(new ZoltanMeshPartitionPolicy("HSFC")));

  ////////////////////////////////////////////////////////////////////
  // INITIALIZE BACKGROUND FLOW FUNCTIONS
  ////////////////////////////////////////////////////////////////////
  BCPtr nullBC = Teuchos::rcp((BC*)NULL);
  RHSPtr nullRHS = Teuchos::rcp((RHS*)NULL);
  IPPtr nullIP = Teuchos::rcp((IP*)NULL);
  SolutionPtr backgroundFlow = Teuchos::rcp(new Solution(mesh, nullBC,
                               nullRHS, nullIP) );

  vector<double> e1(2); // (1,0)
  e1[0] = 1;
  vector<double> e2(2); // (0,1)
  e2[1] = 1;

  FunctionPtr u_prev = Teuchos::rcp( new PreviousSolutionFunction(backgroundFlow, u) );
  FunctionPtr beta = e1 * u_prev + Teuchos::rcp( new ConstantVectorFunction( e2 ) );

  ////////////////////////////////////////////////////////////////////
  // DEFINE BILINEAR FORM
  ////////////////////////////////////////////////////////////////////

  // v:
  // (sigma, grad v)_K - (sigma_hat_n, v)_dK - (u, beta dot grad v) + (u_hat * n dot beta, v)_dK
  bf->addTerm( -u, beta * v->grad());
  bf->addTerm( fhat, v);

  // ==================== SET INITIAL GUESS ==========================
  mesh->registerSolution(backgroundFlow);
  FunctionPtr zero = Teuchos::rcp( new ConstantScalarFunction(0.0) );
  FunctionPtr u0 = Teuchos::rcp( new U0 );

  map<int, Teuchos::RCP<Function> > functionMap;
  functionMap[u->ID()] = u0;

  backgroundFlow->projectOntoMesh(functionMap);
  // ==================== END SET INITIAL GUESS ==========================

  ////////////////////////////////////////////////////////////////////
  // DEFINE INNER PRODUCT
  ////////////////////////////////////////////////////////////////////
  IPPtr ip = Teuchos::rcp( new IP );
  ip->addTerm( v );
  ip->addTerm( beta * v->grad() );

  ////////////////////////////////////////////////////////////////////
  // DEFINE RHS
  ////////////////////////////////////////////////////////////////////
  Teuchos::RCP<RHSEasy> rhs = Teuchos::rcp( new RHSEasy );
  FunctionPtr u_prev_squared_div2 = 0.5 * u_prev * u_prev;
  rhs->addTerm( (e1 * u_prev_squared_div2 + e2 * u_prev) * v->grad());

  ////////////////////////////////////////////////////////////////////
  // DEFINE DIRICHLET BC
  ////////////////////////////////////////////////////////////////////
  Teuchos::RCP<BCEasy> inflowBC = Teuchos::rcp( new BCEasy );

  // Create spatial filters
  SpatialFilterPtr bottomBoundary = Teuchos::rcp( new BottomBoundary );
  SpatialFilterPtr leftBoundary = Teuchos::rcp( new LeftBoundary );
  SpatialFilterPtr rightBoundary = Teuchos::rcp( new LeftBoundary );

  // Create BCs
  FunctionPtr n = Teuchos::rcp( new UnitNormalFunction );
  FunctionPtr u0_squared_div_2 = 0.5 * u0 * u0;
  SimpleFunction* u0Ptr = static_cast<SimpleFunction *>(u0.get());
  double u0Left = u0Ptr->value(0,0);
  double u0Right = u0Ptr->value(1.0,0);
  FunctionPtr leftVal = Teuchos::rcp( new ConstantScalarFunction( -0.5*u0Left*u0Left ) );
  FunctionPtr rightVal = Teuchos::rcp( new ConstantScalarFunction( 0.5*u0Right*u0Right ) );
  inflowBC->addDirichlet(fhat, bottomBoundary, -u0 );
  inflowBC->addDirichlet(fhat, leftBoundary, leftVal );
  inflowBC->addDirichlet(fhat, rightBoundary, rightVal );

  ////////////////////////////////////////////////////////////////////
  // CREATE SOLUTION OBJECT
  ////////////////////////////////////////////////////////////////////
  Teuchos::RCP<Solution> solution = Teuchos::rcp(new Solution(mesh, inflowBC, rhs, ip));
  mesh->registerSolution(solution);

  if (enforceLocalConservation)
  {
    FunctionPtr zero = Teuchos::rcp( new ConstantScalarFunction(0.0) );
    solution->lagrangeConstraints()->addConstraint(fhat == zero);
  }

  ////////////////////////////////////////////////////////////////////
  // DEFINE REFINEMENT STRATEGY
  ////////////////////////////////////////////////////////////////////
  Teuchos::RCP<RefinementStrategy> refinementStrategy;
  refinementStrategy = Teuchos::rcp(new RefinementStrategy(solution,energyThreshold));

  ////////////////////////////////////////////////////////////////////
  // SOLVE
  ////////////////////////////////////////////////////////////////////

  for (int refIndex=0; refIndex<=numRefs; refIndex++)
  {
    double L2Update = 1e7;
    int iterCount = 0;
    while (L2Update > nonlinearRelativeEnergyTolerance && iterCount < maxNewtonIterations)
    {
      solution->solve();
      L2Update = solution->L2NormOfSolutionGlobal(u->ID());
      cout << "L2 Norm of Update = " << L2Update << endl;
      // backgroundFlow->clear();
      backgroundFlow->addSolution(solution, newtonStepSize);
      iterCount++;
    }
    cout << endl;

    // check conservation
    VarPtr testOne = varFactory.testVar("1", CONSTANT_SCALAR);
    // Create a fake bilinear form for the testing
    BFPtr fakeBF = Teuchos::rcp( new BF(varFactory) );
    // Define our mass flux
    FunctionPtr massFlux = Teuchos::rcp( new PreviousSolutionFunction(solution, fhat) );
    LinearTermPtr massFluxTerm = massFlux * testOne;

    Teuchos::RCP<shards::CellTopology> quadTopoPtr = Teuchos::rcp(new shards::CellTopology(shards::getCellTopologyData<shards::Quadrilateral<4> >() ));
    DofOrderingFactory dofOrderingFactory(fakeBF);
    int fakeTestOrder = H1Order;
    DofOrderingPtr testOrdering = dofOrderingFactory.testOrdering(fakeTestOrder, *quadTopoPtr);

    int testOneIndex = testOrdering->getDofIndex(testOne->ID(),0);
    vector< ElementTypePtr > elemTypes = mesh->elementTypes(); // global element types
    map<int, double> massFluxIntegral; // cellID -> integral
    double maxMassFluxIntegral = 0.0;
    double totalMassFlux = 0.0;
    double totalAbsMassFlux = 0.0;
    for (vector< ElementTypePtr >::iterator elemTypeIt = elemTypes.begin(); elemTypeIt != elemTypes.end(); elemTypeIt++)
    {
      ElementTypePtr elemType = *elemTypeIt;
      vector< ElementPtr > elems = mesh->elementsOfTypeGlobal(elemType);
      vector<int> cellIDs;
      for (int i=0; i<elems.size(); i++)
      {
        cellIDs.push_back(elems[i]->cellID());
      }
      FieldContainer<double> physicalCellNodes = mesh->physicalCellNodesGlobal(elemType);
      BasisCachePtr basisCache = Teuchos::rcp( new BasisCache(elemType,mesh) );
      basisCache->setPhysicalCellNodes(physicalCellNodes,cellIDs,true); // true: create side caches
      FieldContainer<double> cellMeasures = basisCache->getCellMeasures();
      FieldContainer<double> fakeRHSIntegrals(elems.size(),testOrdering->totalDofs());
      massFluxTerm->integrate(fakeRHSIntegrals,testOrdering,basisCache,true); // true: force side evaluation
      for (int i=0; i<elems.size(); i++)
      {
        int cellID = cellIDs[i];
        // pick out the ones for testOne:
        massFluxIntegral[cellID] = fakeRHSIntegrals(i,testOneIndex);
      }
      // find the largest:
      for (int i=0; i<elems.size(); i++)
      {
        int cellID = cellIDs[i];
        maxMassFluxIntegral = max(abs(massFluxIntegral[cellID]), maxMassFluxIntegral);
      }
      for (int i=0; i<elems.size(); i++)
      {
        int cellID = cellIDs[i];
        maxMassFluxIntegral = max(abs(massFluxIntegral[cellID]), maxMassFluxIntegral);
        totalMassFlux += massFluxIntegral[cellID];
        totalAbsMassFlux += abs( massFluxIntegral[cellID] );
      }
    }
    if (rank==0)
    {
      cout << endl;
      cout << "largest mass flux: " << maxMassFluxIntegral << endl;
      cout << "total mass flux: " << totalMassFlux << endl;
      cout << "sum of mass flux absolute value: " << totalAbsMassFlux << endl;
      cout << endl;

      stringstream outfile;
      outfile << "burgers_" << refIndex;
      backgroundFlow->writeToVTK(outfile.str(), 5);
    }

    if (refIndex < numRefs)
      refinementStrategy->refine(rank==0); // print to console on rank 0
  }

  return 0;
}