/// <summary>
///
/// </summary>
/// <param name="jCell"></param>
/// <param name="AcceptedMask"></param>
/// <param name="Phi"></param>
/// <param name="gradPhi"></param>
/// <param name="__DiffusionCoeff">Output: if artificial diffusion is turned</param>
/// <param name="MaxAllowedPhi">Input: upper threshold for the values of <paramref name="Phi"/> in cell <see cref="jCell"/>.</param>
/// <param name="MinAllowedPhi">Input: lower threshold for the values of <paramref name="Phi"/> in cell <see cref="jCell"/>.</param>
/// <returns></returns>
public bool LocalSolve_Iterative(int jCell, BitArray AcceptedMask, SinglePhaseField Phi, VectorField <SinglePhaseField> gradPhi, SinglePhaseField __DiffusionCoeff, double MaxAllowedPhi, double MinAllowedPhi)
{
//this.LocalSolve_Geometric(jCell, AcceptedMask, Phi, +1, out MinAllowedPhi, out MaxAllowedPhi);) {
int N = this.LevelSetBasis.GetLength(jCell);
int i0G = this.LevelSetMapping.GlobalUniqueCoordinateIndex(0, jCell, 0);
int i0L = this.LevelSetMapping.LocalUniqueCoordinateIndex(0, jCell, 0);
SinglePhaseField __AcceptedMask = new SinglePhaseField(new Basis(this.GridDat, 0), "accepted");
for (int j = 0; j < AcceptedMask.Length; j++)
{
__AcceptedMask.SetMeanValue(j, AcceptedMask[j] ? 1.0 : 0.0);
}
// subgrid on which we are working, consisting only of one cell
SubGrid jCellGrid = new SubGrid(new CellMask(this.GridDat, Chunk.GetSingleElementChunk(jCell)));
// create spatial operator
IEvaluatorNonLin evo;
{
SpatialOperator op = new SpatialOperator(1, 2, 1, QuadOrderFunc.NonLinear(2), "Phi", "dPhi_dx0", "dPhi_dx1", "cod1");
op.EquationComponents["cod1"].Add(new ReinitOperator());
op.EdgeQuadraturSchemeProvider = g => (new EdgeQuadratureScheme(domain: EdgeMask.GetEmptyMask(g)));
op.VolumeQuadraturSchemeProvider = g => (new CellQuadratureScheme(domain: jCellGrid.VolumeMask));
op.Commit();
evo = op.GetEvaluatorEx(Phi.Mapping.Fields, gradPhi.Mapping.Fields, Phi.Mapping);
evo.ActivateSubgridBoundary(jCellGrid.VolumeMask, subGridBoundaryTreatment: SubGridBoundaryModes.InnerEdge);
}
// create artificial diffusion operator
MultidimensionalArray DiffMtx;
double[] DiffRhs;
SpatialOperator dop;
{
double penaltyBase = this.LevelSetBasis.Degree + 2;
penaltyBase = penaltyBase.Pow2();
dop = (new ArtificialViscosity(AcceptedMask, penaltyBase, GridDat.Cells.h_min, jCell, -1.0)).Operator(1);
MsrMatrix _DiffMtx = new MsrMatrix(this.LevelSetMapping, this.LevelSetMapping);
double[] _DiffRhs = new double[this.LevelSetMapping.LocalLength];
dop.ComputeMatrixEx(this.LevelSetMapping, new DGField[] { Phi, null, null }, this.LevelSetMapping,
_DiffMtx, _DiffRhs, OnlyAffine: false,
edgeQuadScheme: (new EdgeQuadratureScheme(domain: jCellGrid.AllEdgesMask)),
volQuadScheme: (new CellQuadratureScheme(domain: jCellGrid.VolumeMask)));
// extract matrix for 'jCell'
DiffMtx = MultidimensionalArray.Create(N, N);
DiffRhs = new double[N];
for (int n = 0; n < N; n++)
{
#if DEBUG
int Lr;
int[] row_cols = null;
double[] row_vals = null;
Lr = _DiffMtx.GetRow(i0G + n, ref row_cols, ref row_vals);
for (int lr = 0; lr < Lr; lr++)
{
int ColIndex = row_cols[lr];
double Value = row_vals[lr];
Debug.Assert((ColIndex >= i0G && ColIndex < i0G + N) || (Value == 0.0), "Matrix is expected to be block-diagonal.");
}
#endif
for (int m = 0; m < N; m++)
{
DiffMtx[n, m] = _DiffMtx[i0G + n, i0G + m];
}
DiffRhs[n] = _DiffRhs[i0L + n];
}
#if DEBUG
var Test = DiffMtx.Transpose();
Test.Acc(-1.0, DiffMtx);
Debug.Assert(Test.InfNorm() <= 1.0e-8);
#endif
}
// find 'good' initial value by geometric solve AND
// thresholds for the maximum an minimal value of Phi
double Range = MaxAllowedPhi - MinAllowedPhi;
MinAllowedPhi -= 0.1 * Range;
MaxAllowedPhi += 0.1 * Range;
// timestep for pseudo-timestepping
double dt = 0.5 * this.GridDat.Cells.h_min[jCell] / (((double)(this.LevelSetBasis.Degree)).Pow2());
DGField[] PlotFields = new DGField[] { Phi, gradPhi[0], gradPhi[1], __DiffusionCoeff, __AcceptedMask };
//Tecplot.Tecplot.PlotFields(Params, "itt_0", "EllipicReinit", 0, 3);
double[] PrevVal = new double[N];
double[] NextVal = new double[N];
Phi.Coordinates.GetRow(jCell, PrevVal);
// pseudo-timestepping
//if(jCell == 80)
// Tecplot.Tecplot.PlotFields(PlotFields, "itt_0", "EllipicReinit", 0, 3);
//Console.Write(" Local solve cell " + jCell + " ... ");
bool converged = false;
double DiffusionCoeff = 0;
int IterGrowCount = 0; // number of iterations in which the residual grew
double LastResi = double.NaN;
for (int iIter = 0; iIter < 1000; iIter++)
{
//Console.Write(" Local solve iteration " + iIter + " ... ");
PerformRKstep(dt, jCell, AcceptedMask, Phi, gradPhi, evo);
__DiffusionCoeff.SetMeanValue(jCell, DiffusionCoeff);
if (jCell == 80)
{
DiffusionCoeff = 0.1;
}
if (DiffusionCoeff > 0)
{
//Console.WriteLine(" Diffusion on.");
double[] _DiffRhs = new double[this.LevelSetMapping.LocalLength];
dop.ComputeMatrixEx(this.LevelSetMapping, new DGField[] { Phi, gradPhi[0], gradPhi[1] }, this.LevelSetMapping,
default(MsrMatrix), _DiffRhs, OnlyAffine: true,
edgeQuadScheme: (new EdgeQuadratureScheme(domain: jCellGrid.AllEdgesMask)),
volQuadScheme: (new CellQuadratureScheme(domain: CellMask.GetEmptyMask(this.GridDat))));
// extract matrix for 'jCell'
for (int n = 0; n < N; n++)
{
DiffRhs[n] = _DiffRhs[i0L + n];
}
PerformArtificialDiffusion(dt * DiffusionCoeff, jCell, Phi, DiffMtx, DiffRhs);
}
Phi.Coordinates.GetRow(jCell, NextVal);
double resi = Math.Sqrt(GenericBlas.L2DistPow2(NextVal, PrevVal) / GenericBlas.L2NormPow2(PrevVal));
double[] A = NextVal;
NextVal = PrevVal;
PrevVal = A;
if (iIter > 0 && resi > LastResi)
{
IterGrowCount++;
}
else
{
IterGrowCount = 0;
}
LastResi = resi;
if (resi < 1.0e-10)
{
converged = true;
break;
}
double maxPhi, minPhi;
Phi.GetExtremalValuesInCell(out minPhi, out maxPhi, jCell);
bool MinAlarm = minPhi < MinAllowedPhi;
bool Maxalarm = maxPhi > MaxAllowedPhi;
bool GrowAlarm = IterGrowCount > 4;
bool IterAlarm = iIter >= 50;
if (MinAlarm || Maxalarm || GrowAlarm)
{
// Diffusion coefficient should be increased
if (DiffusionCoeff == 0)
{
DiffusionCoeff = 1.0e-2;
}
else
{
if (DiffusionCoeff < 1.0e3)
{
DiffusionCoeff *= 2;
}
}
//Console.WriteLine(" increasing Diffusion: {0}, Alarms : {1}{2}{3}{4}", DiffusionCoeff, MinAlarm ? 1 : 0, Maxalarm ? 1 : 0, GrowAlarm ? 1 : 0, IterAlarm ? 1 : 0);
}
//if(jCell == 80 && iIter < 100)
// Tecplot.Tecplot.PlotFields(PlotFields, "itt_" + (iIter + 1), "EllipicReinit", iIter + 1, 3);
}
return(converged);
}
