void acarFluid::step() {
//smooth level set?
smoothLevelSet(levelset, levelsetSmooth);
//solve for stream function using the level set
fftw_execute( levelsetPlan);
solvePoisson(levelsetF, streamF);
fftw_execute(streamPlanI);
//use stream function to compute velocity
computeVelocity(stream, velocityU, velocityV);
//use velocity to advect (level set?, smoothed level set?, vorticity?)
advectLinear(levelset, levelsetTemp);
for(int i=0;i<width*height;++i) levelset[i] = levelsetTemp[i];
//repeat
}
//////////////////////////////////////////////////////////////////////
// project into divergence free field
//////////////////////////////////////////////////////////////////////
void FLUID_3D_MIC::project()
{
TIMER functionTimer(__FUNCTION__);
int index, x, y, z;
setObstacleBoundaries();
// copy out the boundaries
if(_domainBcLeft == 0)
_velocity.setNeumannX();
else
_velocity.setZeroX();
if(_domainBcTop == 0)
_velocity.setNeumannY();
else
_velocity.setZeroY();
if(_domainBcFront == 0)
_velocity.setNeumannZ();
else
_velocity.setZeroZ();
// calculate divergence
index = _slabSize + _xRes + 1;
for (z = 1; z < _zRes - 1; z++, index += 2 * _xRes)
for (y = 1; y < _yRes - 1; y++, index += 2)
for (x = 1; x < _xRes - 1; x++, index++)
{
Real xright = _velocity[index + 1][0];
Real xleft = _velocity[index - 1][0];
Real yup = _velocity[index + _xRes][1];
Real ydown = _velocity[index - _xRes][1];
Real ztop = _velocity[index + _slabSize][2];
Real zbottom = _velocity[index - _slabSize][2];
if(_obstacles[index+1]) xright = - _velocity[index][0];
if(_obstacles[index-1]) xleft = - _velocity[index][0];
if(_obstacles[index+_xRes]) yup = - _velocity[index][1];
if(_obstacles[index-_xRes]) ydown = - _velocity[index][1];
if(_obstacles[index+_slabSize]) ztop = - _velocity[index][2];
if(_obstacles[index-_slabSize]) zbottom = - _velocity[index][2];
_divergence[index] = -_dx * 0.5f * (
xright - xleft +
yup - ydown +
ztop - zbottom );
_pressure[index] = 0.0f;
}
_pressure.copyBorderAll();
_cachedDivergence = _divergence;
// solve Poisson equation
solvePoisson(_pressure, _divergence, _obstacles, false);
_cachedPressure = _pressure;
// project out solution -- more matrix-friendly version
Real invDx = 1.0f / _dx;
index = _slabSize + _xRes + 1;
for (z = 1; z < _zRes - 1; z++, index += 2 * _xRes)
for (y = 1; y < _yRes - 1; y++, index += 2)
for (x = 1; x < _xRes - 1; x++, index++)
{
if (x == 1)
_velocity[index][0] -= (_pressure[index + 1] - _pressure[index]) * invDx;
else if (x == _xRes - 2)
_velocity[index][0] -= (_pressure[index] - _pressure[index - 1]) * invDx;
else
_velocity[index][0] -= 0.5f * (_pressure[index + 1] - _pressure[index - 1]) * invDx;
if (y == 1)
_velocity[index][1] -= (_pressure[index + _xRes] - _pressure[index]) * invDx;
else if (y == _yRes - 2)
_velocity[index][1] -= (_pressure[index] - _pressure[index - _xRes]) * invDx;
else
_velocity[index][1] -= 0.5f * (_pressure[index + _xRes] - _pressure[index - _xRes]) * invDx;
if (z == 1)
_velocity[index][2] -= (_pressure[index + _slabSize] - _pressure[index]) * invDx;
else if (z == _zRes - 2)
_velocity[index][2] -= (_pressure[index] - _pressure[index - _slabSize]) * invDx;
else
_velocity[index][2] -= 0.5f * (_pressure[index + _slabSize] - _pressure[index - _slabSize]) * invDx;
}
}
