/**
* Simple Parabolic PDE u' = del squared u
*
* With u = 0 on the boundaries of the unit cube. Subject to the initial
* condition u(0,x,y,z)=sin( PI x)sin( PI y)sin( PI z).
*/
void TestSimpleLinearParabolicSolver3DZeroDirich()
{
// read mesh on [0,1]x[0,1]x[0,1]
TrianglesMeshReader<3,3> mesh_reader("mesh/test/data/cube_136_elements");
TetrahedralMesh<3,3> mesh;
mesh.ConstructFromMeshReader(mesh_reader);
// Instantiate PDE object
HeatEquation<3> pde;
// Boundary conditions - zero dirichlet everywhere on boundary
BoundaryConditionsContainer<3,3,1> bcc;
bcc.DefineZeroDirichletOnMeshBoundary(&mesh);
// Solver
SimpleLinearParabolicSolver<3,3> solver(&mesh,&pde,&bcc);
/*
* Choose initial condition sin(x*pi)*sin(y*pi)*sin(z*pi) as
* this is an eigenfunction of the heat equation.
*/
std::vector<double> init_cond(mesh.GetNumNodes());
for (unsigned i=0; i<mesh.GetNumNodes(); i++)
{
double x = mesh.GetNode(i)->GetPoint()[0];
double y = mesh.GetNode(i)->GetPoint()[1];
double z = mesh.GetNode(i)->GetPoint()[2];
init_cond[i] = sin(x*M_PI)*sin(y*M_PI)*sin(z*M_PI);
}
Vec initial_condition = PetscTools::CreateVec(init_cond);
double t_end = 0.1;
solver.SetTimes(0, t_end);
solver.SetTimeStep(0.001);
solver.SetInitialCondition(initial_condition);
Vec result = solver.Solve();
ReplicatableVector result_repl(result);
// Check solution is u = e^{-3*t*pi*pi} sin(x*pi)*sin(y*pi)*sin(z*pi), t=0.1
for (unsigned i=0; i<result_repl.GetSize(); i++)
{
double x = mesh.GetNode(i)->GetPoint()[0];
double y = mesh.GetNode(i)->GetPoint()[1];
double z = mesh.GetNode(i)->GetPoint()[2];
double u = exp(-3*t_end*M_PI*M_PI)*sin(x*M_PI)*sin(y*M_PI)*sin(z*M_PI);
TS_ASSERT_DELTA(result_repl[i], u, 0.1);
}
PetscTools::Destroy(initial_condition);
PetscTools::Destroy(result);
}
void TestDefineZeroDirichletOnMeshBoundary()
{
// Load a 2D square mesh with 1 central non-boundary node
TrianglesMeshReader<2,2> mesh_reader("mesh/test/data/square_4_elements");
TetrahedralMesh<2,2> mesh;
mesh.ConstructFromMeshReader(mesh_reader);
BoundaryConditionsContainer<2,2,1> bcc;
bcc.DefineZeroDirichletOnMeshBoundary(&mesh);
// Check boundary nodes have the right condition
for (int i=0; i<4; i++)
{
double value = bcc.GetDirichletBCValue(mesh.GetNode(i));
TS_ASSERT_DELTA(value, 0.0, 1e-12);
}
// Check non-boundary node has no condition
TS_ASSERT(!bcc.HasDirichletBoundaryCondition(mesh.GetNode(4)));
}
void TestSolveAndWriteResultsToFileMethod()
{
// Create mesh of the domain [0,1]x[0,1]
TrianglesMeshReader<2,2> mesh_reader("mesh/test/data/square_128_elements");
TetrahedralMesh<2,2> mesh;
mesh.ConstructFromMeshReader(mesh_reader);
// Create PDE system object
HeatEquationForCoupledOdeSystem<2> pde;
// Define zero Dirichlet boundary conditions on entire boundary
BoundaryConditionsContainer<2,2,1> bcc;
bcc.DefineZeroDirichletOnMeshBoundary(&mesh);
// Create the correct number of ODE systems
double a = 5.0;
std::vector<AbstractOdeSystemForCoupledPdeSystem*> ode_systems;
for (unsigned i=0; i<mesh.GetNumNodes(); i++)
{
ode_systems.push_back(new OdeSystemForCoupledHeatEquation(a));
}
// Create PDE system solver
LinearParabolicPdeSystemWithCoupledOdeSystemSolver<2,2,1> solver(&mesh, &pde, &bcc, ode_systems);
// Set end time and timestep (end time is not a multiple of timestep, for coverage)
double t_end = 0.105;
/*
* Set initial condition
*
* u(x,y,0) = sin(pi*x)*sin(pi*y),
*
* which is an eigenfunction of the heat equation.
*/
std::vector<double> init_cond(mesh.GetNumNodes());
for (unsigned i=0; i<mesh.GetNumNodes(); i++)
{
double x = mesh.GetNode(i)->GetPoint()[0];
double y = mesh.GetNode(i)->GetPoint()[1];
init_cond[i] = sin(M_PI*x)*sin(M_PI*y);
}
Vec initial_condition = PetscTools::CreateVec(init_cond);
// Need an output folder
TS_ASSERT_THROWS_THIS(solver.SolveAndWriteResultsToFile(),
"SetOutputDirectory() must be called prior to SolveAndWriteResultsToFile()");
solver.SetOutputDirectory("TestHeatEquationForCoupledOdeSystemIn2dWithZeroDirichletWithOutput");
// Need a time interval
TS_ASSERT_THROWS_THIS(solver.SolveAndWriteResultsToFile(),
"SetTimes() must be called prior to SolveAndWriteResultsToFile()");
solver.SetTimes(0, t_end);
// Need a timestep
TS_ASSERT_THROWS_THIS(solver.SolveAndWriteResultsToFile(),
"SetTimeStep() must be called prior to SolveAndWriteResultsToFile()");
solver.SetTimeStep(0.01);
// Need sampling interval
TS_ASSERT_THROWS_THIS(solver.SolveAndWriteResultsToFile(),
"SetSamplingTimeStep() must be called prior to SolveAndWriteResultsToFile()");
solver.SetSamplingTimeStep(0.1);
// Need initial condition
TS_ASSERT_THROWS_THIS(solver.SolveAndWriteResultsToFile(),
"SetInitialCondition() must be called prior to SolveAndWriteResultsToFile()");
solver.SetInitialCondition(initial_condition);
solver.SolveAndWriteResultsToFile();
//#ifdef CHASTE_VTK
///\todo #1967 Check that the file was output and has expected content
//#endif // CHASTE_VTK
// Tidy up
PetscTools::Destroy(initial_condition);
}
void TestHeatEquationWithCoupledOdeSystemIn2dWithZeroDirichlet()
{
// Create mesh of the domain [0,1]x[0,1]
TrianglesMeshReader<2,2> mesh_reader("mesh/test/data/square_4096_elements");
TetrahedralMesh<2,2> mesh;
mesh.ConstructFromMeshReader(mesh_reader);
// Create PDE system object
HeatEquationForCoupledOdeSystem<2> pde;
// Define zero Dirichlet boundary conditions on entire boundary
BoundaryConditionsContainer<2,2,1> bcc;
bcc.DefineZeroDirichletOnMeshBoundary(&mesh);
// Create the correct number of ODE systems
double a = 5.0;
std::vector<AbstractOdeSystemForCoupledPdeSystem*> ode_systems;
for (unsigned i=0; i<mesh.GetNumNodes(); i++)
{
ode_systems.push_back(new OdeSystemForCoupledHeatEquation(a));
}
// Create PDE system solver
LinearParabolicPdeSystemWithCoupledOdeSystemSolver<2,2,1> solver(&mesh, &pde, &bcc, ode_systems);
// Set end time and timestep
double t_end = 0.01;
solver.SetTimes(0, t_end);
solver.SetTimeStep(0.001);
/*
* Set initial condition
*
* u(x,y,0) = sin(pi*x)*sin(pi*y),
*
* which is an eigenfunction of the heat equation.
*/
std::vector<double> init_cond(mesh.GetNumNodes());
for (unsigned i=0; i<mesh.GetNumNodes(); i++)
{
double x = mesh.GetNode(i)->GetPoint()[0];
double y = mesh.GetNode(i)->GetPoint()[1];
init_cond[i] = sin(M_PI*x)*sin(M_PI*y);
}
Vec initial_condition = PetscTools::CreateVec(init_cond);
solver.SetInitialCondition(initial_condition);
// Solve PDE system and store result
Vec result = solver.Solve();
ReplicatableVector result_repl(result);
/*
* Test that solution is given by
*
* u(x,y,t) = e^{-2*pi*pi*t} sin(pi*x)*sin(pi*y),
* v(x,y,t) = 1 + (1 - e^{-2*pi*pi*t})*sin(pi*x)*sin(pi*y)*a/(2*pi*pi),
*
* with t = t_end.
*/
for (unsigned i=0; i<result_repl.GetSize(); i++)
{
double x = mesh.GetNode(i)->GetPoint()[0];
double y = mesh.GetNode(i)->GetPoint()[1];
double u = exp(-2*M_PI*M_PI*t_end)*sin(M_PI*x)*sin(M_PI*y);
double v = 1.0 + (a/(2*M_PI*M_PI))*(1 - exp(-2*M_PI*M_PI*t_end))*sin(M_PI*x)*sin(M_PI*y);
TS_ASSERT_DELTA(result_repl[i], u, 0.01);
TS_ASSERT_DELTA(ode_systems[i]->rGetStateVariables()[0], v, 0.01);
}
// Tidy up
PetscTools::Destroy(initial_condition);
PetscTools::Destroy(result);
}
