/// <summary>
///
/// </summary>
/// <param name="dt"></param>
/// <param name="velocity"></param>
/// <returns></returns>
public override double[] ComputeChangerate(double dt, ConventionalDGField[] velocity, double[] current_FLSprop)
{
GridData grdat = (GridData)velocity[0].GridDat;
FieldEvaluation fEval = new FieldEvaluation(grdat);
MultidimensionalArray VelocityAtSamplePoints = MultidimensionalArray.Create(current_interfaceP.Lengths);
int outP = fEval.Evaluate(1, velocity, current_interfaceP, 0, VelocityAtSamplePoints);
if (outP != 0)
{
throw new Exception("points outside the grid for fieldevaluation");
}
// change rate for the material points is the velocity at the points
if (FourierEvolve == Fourier_Evolution.MaterialPoints)
{
double[] velAtP = new double[2 * numFp];
for (int sp = 0; sp < numFp; sp++)
{
velAtP[sp * 2] = VelocityAtSamplePoints[sp, 0];
velAtP[sp * 2 + 1] = VelocityAtSamplePoints[sp, 1];
}
return(velAtP);
}
// compute an infinitesimal change of sample points at the Fourier points/ change of Fourier modes
MultidimensionalArray interfaceP_evo = current_interfaceP.CloneAs();
double dt_infin = dt * 1e-3;
interfaceP_evo.Acc(dt_infin, VelocityAtSamplePoints);
RearrangeOntoPeriodicDomain(interfaceP_evo);
double[] samplP_change = current_samplP.CloneAs();
InterpolateOntoFourierPoints(interfaceP_evo, samplP_change);
if (FourierEvolve == Fourier_Evolution.FourierPoints)
{
samplP_change.AccV(-1.0, current_samplP);
samplP_change.ScaleV(1.0 / dt_infin);
return(samplP_change);
}
else
if (FourierEvolve == Fourier_Evolution.FourierModes)
{
Complex[] samplP_complex = new Complex[numFp];
for (int sp = 0; sp < numFp; sp++)
{
samplP_complex[sp] = (Complex)samplP_change[sp];
}
Complex[] DFT_change = DFT.NaiveForward(samplP_complex, FourierOptions.Matlab);
double[] DFT_change_double = new double[2 * numFp];
for (int sp = 0; sp < numFp; sp++)
{
DFT_change_double[sp * 2] = (DFT_change[sp].Real - DFT_coeff[sp].Real) / dt_infin;
DFT_change_double[sp * 2 + 1] = (DFT_change[sp].Imaginary - DFT_coeff[sp].Imaginary) / dt_infin;
}
return(DFT_change_double);
}
else
{
throw new ArgumentException();
}
}
/// <summary>
///
/// </summary>
/// <param name="velocity"></param>
/// <returns></returns>
public override double[] ComputeChangerate(double dt, ConventionalDGField[] velocity, double[] current_FLSprop)
{
setMaterialInterfacePoints(current_FLSprop);
GridData grdat = (GridData)(velocity[0].GridDat);
FieldEvaluation fEval = new FieldEvaluation(grdat);
// Movement of the material interface points
MultidimensionalArray VelocityAtSamplePointsXY = MultidimensionalArray.Create(current_interfaceP.Lengths);
int outP = fEval.Evaluate(1, velocity, current_interfaceP, 0, VelocityAtSamplePointsXY);
if (outP != 0)
{
throw new Exception("points outside the grid for fieldevaluation");
}
int numIp = current_interfaceP.Lengths[0];
// change rate for the material points is the velocity at the points
if (FourierEvolve == Fourier_Evolution.MaterialPoints)
{
double[] velAtP = new double[2 * numIp];
for (int sp = 0; sp < numIp; sp++)
{
velAtP[sp * 2] = VelocityAtSamplePointsXY[sp, 0];
velAtP[(sp * 2) + 1] = VelocityAtSamplePointsXY[sp, 1];
}
return(velAtP);
}
// compute an infinitesimal change of sample points at the Fourier points/ change of Fourier modes
MultidimensionalArray interfaceP_evo = current_interfaceP.CloneAs();
double dt_infin = dt * 1e-3;
interfaceP_evo.Acc(dt_infin, VelocityAtSamplePointsXY);
// Movement of the center point
MultidimensionalArray center_evo = center.CloneAs();
MultidimensionalArray VelocityAtCenter = center.CloneAs();
switch (CenterMove)
{
case CenterMovement.None: {
VelocityAtCenter.Clear();
break;
}
case CenterMovement.Reconstructed: {
center_evo = GetGeometricCenter(interfaceP_evo);
//Console.WriteLine("center_evo = ({0}, {1}) / center = ({2}, {3})", center_evo[0, 0], center_evo[0, 1], center[0, 0], center[0, 1]);
MultidimensionalArray center_change = center_evo.CloneAs();
center_change.Acc(-1.0, center);
center_change.Scale(1.0 / dt_infin);
VelocityAtCenter[0, 0] = center_change[0, 0];
VelocityAtCenter[0, 1] = center_change[0, 1];
break;
}
case CenterMovement.VelocityAtCenter: {
outP = fEval.Evaluate(1, velocity, center, 0, VelocityAtCenter);
if (outP != 0)
{
throw new Exception("center point outside the grid for fieldevaluation");
}
center_evo.Acc(dt_infin, VelocityAtCenter);
break;
}
}
//Console.WriteLine("Velocity at Center point = ({0}, {1})", VelocityAtCenter[0, 0], VelocityAtCenter[0, 1]);
// transform to polar coordiantes
MultidimensionalArray interP_evo_polar = interfaceP_polar.CloneAs();
for (int sp = 0; sp < numIp; sp++)
{
double x_c = interfaceP_evo[sp, 0] - center_evo[0, 0];
double y_c = interfaceP_evo[sp, 1] - center_evo[0, 1];
double theta = Math.Atan2(y_c, x_c);
if (theta < 0)
{
theta = Math.PI * 2 + theta;
}
;
interP_evo_polar[sp, 0] = theta;
interP_evo_polar[sp, 1] = Math.Sqrt(x_c.Pow2() + y_c.Pow2());
}
RearrangeOntoPeriodicDomain(interP_evo_polar);
double[] samplP_change = current_samplP.CloneAs();
InterpolateOntoFourierPoints(interP_evo_polar, samplP_change);
if (FourierEvolve == Fourier_Evolution.FourierPoints)
{
samplP_change.AccV(-1.0, current_samplP);
samplP_change.ScaleV(1.0 / dt_infin);
double[] FPchange = new double[numFp + 2];
FPchange[0] = VelocityAtCenter[0, 0];
FPchange[1] = VelocityAtCenter[0, 1];
for (int p = 0; p < numFp; p++)
{
FPchange[p + 2] = samplP_change[p];
}
return(FPchange);
}
else
if (FourierEvolve == Fourier_Evolution.FourierModes)
{
Complex[] samplP_complex = new Complex[numFp];
for (int sp = 0; sp < numFp; sp++)
{
samplP_complex[sp] = (Complex)samplP_change[sp];
}
Complex[] DFTchange = DFT.NaiveForward(samplP_complex, FourierOptions.Matlab);
double[] DFTchange_double = new double[2 * numFp + 2];
DFTchange_double[0] = VelocityAtCenter[0, 0];
DFTchange_double[1] = VelocityAtCenter[0, 1];
for (int sp = 0; sp < numFp; sp++)
{
DFTchange_double[2 + (sp * 2)] = (DFTchange[sp].Real - DFT_coeff[sp].Real) / dt_infin;
DFTchange_double[2 + (sp * 2) + 1] = (DFTchange[sp].Imaginary - DFT_coeff[sp].Imaginary) / dt_infin;
}
return(DFTchange_double);
}
else
{
throw new ArgumentException();
}
}