WIP: Pull Request for a complete Solver package #2
@ -36,6 +36,13 @@ te 100.0 # final time
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dt 0.02 # time stepsize
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tau 0.5 # safety factor for time stepsize control (<0 constant delt)
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# Multigrid data:
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# ---------
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levels 3 # Multigrid levels
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presmooth 5 # Pre-smoothning iterations
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postsmooth 5 # Post-smoothning iterations
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# Pressure Iteration Data:
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# -----------------------
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@ -43,5 +50,4 @@ itermax 500 # maximal number of pressure iteration in one time step
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eps 0.00001 # stopping tolerance for pressure iteration
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omg 1.8 # relaxation parameter for SOR iteration
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gamma 0.9 # upwind differencing factor gamma
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levels 5 # Multigrid levels
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#===============================================================================
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@ -26,8 +26,8 @@ p_init 0.0 # initial value for pressure
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xlength 1.0 # domain size in x-direction
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ylength 1.0 # domain size in y-direction
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imax 800 # number of interior cells in x-direction
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jmax 800 # number of interior cells in y-direction
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imax 128 # number of interior cells in x-direction
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jmax 128 # number of interior cells in y-direction
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# Time Data:
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# ---------
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@ -36,6 +36,13 @@ te 10.0 # final time
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dt 0.02 # time stepsize
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tau 0.5 # safety factor for time stepsize control (<0 constant delt)
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# Multigrid data:
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# ---------
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levels 2 # Multigrid levels
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presmooth 20 # Pre-smoothning iterations
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postsmooth 5 # Post-smoothning iterations
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# Solver Data:
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# -----------------------
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@ -44,5 +51,4 @@ eps 0.001 # stopping tolerance for pressure iteration
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rho 0.5
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omg 1.7 # relaxation parameter for SOR iteration
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gamma 0.9 # upwind differencing factor gamma
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levels 5 # Multigrid levels
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#===============================================================================
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@ -24,6 +24,8 @@ void initParameter(Parameter* param)
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param->gamma = 0.9;
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param->tau = 0.5;
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param->levels = 5;
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param->presmooth = 5;
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param->postsmooth = 5;
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}
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void readParameter(Parameter* param, const char* filename)
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@ -79,6 +81,8 @@ void readParameter(Parameter* param, const char* filename)
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PARSE_REAL(u_init);
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PARSE_REAL(v_init);
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PARSE_REAL(p_init);
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PARSE_INT(presmooth);
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PARSE_INT(postsmooth);
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}
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}
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@ -18,6 +18,7 @@ typedef struct {
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char* name;
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int bcLeft, bcRight, bcBottom, bcTop;
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double u_init, v_init, p_init;
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int presmooth, postsmooth;
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} Parameter;
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void initParameter(Parameter*);
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@ -84,6 +84,37 @@ static double smooth(Solver* s, double* p, double* rhs, int level, int imax, int
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jsw = 1;
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for (pass = 0; pass < 2; pass++) {
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isw = jsw;
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for (int j = 1; j < jmax + 1; j++) {
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for (int i = isw; i < imax + 1; i += 2) {
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P(i, j) -= factor * (RHS(i, j) -
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((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 +
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(P(i, j + 1) - 2.0 * P(i, j) + P(i, j - 1)) * idy2));
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}
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isw = 3 - isw;
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}
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jsw = 3 - jsw;
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}
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}
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static double calculateResidual(Solver* s, double* p, double* rhs, int level, int imax, int jmax)
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{
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double dx2 = s->grid->dx * s->grid->dx;
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double dy2 = s->grid->dy * s->grid->dy;
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double idx2 = 1.0 / dx2;
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double idy2 = 1.0 / dy2;
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double factor = s->omega * 0.5 * (dx2 * dy2) / (dx2 + dy2);
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double* r = s->r[level];
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double res = 1.0;
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int pass, jsw, isw;
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jsw = 1;
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for (pass = 0; pass < 2; pass++) {
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isw = jsw;
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@ -94,7 +125,6 @@ static double smooth(Solver* s, double* p, double* rhs, int level, int imax, int
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((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 +
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(P(i, j + 1) - 2.0 * P(i, j) + P(i, j - 1)) * idy2);
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P(i, j) -= (factor * R(i, j));
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res += (R(i, j) * R(i, j));
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}
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isw = 3 - isw;
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@ -110,7 +140,7 @@ static double multiGrid(Solver* s, double* p, double* rhs, int level, int imax,
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{
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double res = 0.0;
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// coarsest level TODO: Use direct solver?
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// coarsest level
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if (level == COARSEST_LEVEL) {
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for (int i = 0; i < 5; i++) {
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smooth(s, p, rhs, level, imax, jmax);
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@ -118,17 +148,18 @@ static double multiGrid(Solver* s, double* p, double* rhs, int level, int imax,
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return res;
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}
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// pre-smoothing TODO: Make smoothing steps configurable?
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for (int i = 0; i < 5; i++) {
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// pre-smoothing
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for (int i = 0; i < s->presmooth; i++) {
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smooth(s, p, rhs, level, imax, jmax);
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if (level == FINEST_LEVEL) setBoundaryCondition(p, imax, jmax);
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}
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res = calculateResidual(s, p, rhs, level, imax, jmax);
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// restrict
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restrictMG(s, level, imax, jmax);
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// MGSolver on residual and error.
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// TODO: What if there is a rest?
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multiGrid(s, s->e[level + 1], s->r[level + 1], level + 1, imax / 2, jmax / 2);
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// prolongate
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@ -139,8 +170,8 @@ static double multiGrid(Solver* s, double* p, double* rhs, int level, int imax,
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if (level == FINEST_LEVEL) setBoundaryCondition(p, imax, jmax);
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// post-smoothing
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for (int i = 0; i < 5; i++) {
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res = smooth(s, p, rhs, level, imax, jmax);
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for (int i = 0; i < s->postsmooth; i++) {
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smooth(s, p, rhs, level, imax, jmax);
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if (level == FINEST_LEVEL) setBoundaryCondition(p, imax, jmax);
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}
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@ -154,6 +185,8 @@ void initSolver(Solver* s, Discretization* d, Parameter* p)
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s->itermax = p->itermax;
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s->levels = p->levels;
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s->grid = &d->grid;
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s->presmooth = p->presmooth;
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s->postsmooth = p->postsmooth;
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int imax = s->grid->imax;
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int jmax = s->grid->jmax;
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@ -18,6 +18,7 @@ typedef struct {
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int itermax;
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int levels;
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double **r, **e;
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int presmooth, postsmooth;
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} Solver;
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extern void initSolver(Solver*, Discretization*, Parameter*);
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