WIP: Pull Request for a complete Solver package #1

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AdityaUjeniya wants to merge 51 commits from (deleted):main into main
6 changed files with 62 additions and 11 deletions
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@ -36,6 +36,13 @@ te 100.0 # final time
dt 0.02 # time stepsize
tau 0.5 # safety factor for time stepsize control (<0 constant delt)
# Multigrid data:
# ---------
levels 3 # Multigrid levels
presmooth 5 # Pre-smoothning iterations
postsmooth 5 # Post-smoothning iterations
# Pressure Iteration Data:
# -----------------------
@ -43,5 +50,4 @@ itermax 500 # maximal number of pressure iteration in one time step
eps 0.00001 # stopping tolerance for pressure iteration
omg 1.8 # relaxation parameter for SOR iteration
gamma 0.9 # upwind differencing factor gamma
levels 5 # Multigrid levels
#===============================================================================

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@ -26,8 +26,8 @@ p_init 0.0 # initial value for pressure
xlength 1.0 # domain size in x-direction
ylength 1.0 # domain size in y-direction
imax 800 # number of interior cells in x-direction
jmax 800 # number of interior cells in y-direction
imax 128 # number of interior cells in x-direction
jmax 128 # number of interior cells in y-direction
# Time Data:
# ---------
@ -36,6 +36,13 @@ te 10.0 # final time
dt 0.02 # time stepsize
tau 0.5 # safety factor for time stepsize control (<0 constant delt)
# Multigrid data:
# ---------
levels 2 # Multigrid levels
presmooth 20 # Pre-smoothning iterations
postsmooth 5 # Post-smoothning iterations
# Solver Data:
# -----------------------
@ -44,5 +51,4 @@ eps 0.001 # stopping tolerance for pressure iteration
rho 0.5
omg 1.7 # relaxation parameter for SOR iteration
gamma 0.9 # upwind differencing factor gamma
levels 5 # Multigrid levels
#===============================================================================

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@ -24,6 +24,8 @@ void initParameter(Parameter* param)
param->gamma = 0.9;
param->tau = 0.5;
param->levels = 5;
param->presmooth = 5;
param->postsmooth = 5;
}
void readParameter(Parameter* param, const char* filename)
@ -79,6 +81,8 @@ void readParameter(Parameter* param, const char* filename)
PARSE_REAL(u_init);
PARSE_REAL(v_init);
PARSE_REAL(p_init);
PARSE_INT(presmooth);
PARSE_INT(postsmooth);
}
}

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@ -18,6 +18,7 @@ typedef struct {
char* name;
int bcLeft, bcRight, bcBottom, bcTop;
double u_init, v_init, p_init;
int presmooth, postsmooth;
} Parameter;
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
jsw = 1;
for (pass = 0; pass < 2; pass++) {
isw = jsw;
for (int j = 1; j < jmax + 1; j++) {
for (int i = isw; i < imax + 1; i += 2) {
P(i, j) -= factor * (RHS(i, j) -
((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 +
(P(i, j + 1) - 2.0 * P(i, j) + P(i, j - 1)) * idy2));
}
isw = 3 - isw;
}
jsw = 3 - jsw;
}
}
static double calculateResidual(Solver* s, double* p, double* rhs, int level, int imax, int jmax)
{
double dx2 = s->grid->dx * s->grid->dx;
double dy2 = s->grid->dy * s->grid->dy;
double idx2 = 1.0 / dx2;
double idy2 = 1.0 / dy2;
double factor = s->omega * 0.5 * (dx2 * dy2) / (dx2 + dy2);
double* r = s->r[level];
double res = 1.0;
int pass, jsw, isw;
jsw = 1;
for (pass = 0; pass < 2; pass++) {
isw = jsw;
@ -94,7 +125,6 @@ static double smooth(Solver* s, double* p, double* rhs, int level, int imax, int
((P(i + 1, j) - 2.0 * P(i, j) + P(i - 1, j)) * idx2 +
(P(i, j + 1) - 2.0 * P(i, j) + P(i, j - 1)) * idy2);
P(i, j) -= (factor * R(i, j));
res += (R(i, j) * R(i, j));
}
isw = 3 - isw;
@ -110,7 +140,7 @@ static double multiGrid(Solver* s, double* p, double* rhs, int level, int imax,
{
double res = 0.0;
// coarsest level TODO: Use direct solver?
// coarsest level
if (level == COARSEST_LEVEL) {
for (int i = 0; i < 5; i++) {
smooth(s, p, rhs, level, imax, jmax);
@ -118,17 +148,18 @@ static double multiGrid(Solver* s, double* p, double* rhs, int level, int imax,
return res;
}
// pre-smoothing TODO: Make smoothing steps configurable?
for (int i = 0; i < 5; i++) {
// pre-smoothing
for (int i = 0; i < s->presmooth; i++) {
smooth(s, p, rhs, level, imax, jmax);
if (level == FINEST_LEVEL) setBoundaryCondition(p, imax, jmax);
}
res = calculateResidual(s, p, rhs, level, imax, jmax);
// restrict
restrictMG(s, level, imax, jmax);
// MGSolver on residual and error.
// TODO: What if there is a rest?
multiGrid(s, s->e[level + 1], s->r[level + 1], level + 1, imax / 2, jmax / 2);
// prolongate
@ -139,8 +170,8 @@ static double multiGrid(Solver* s, double* p, double* rhs, int level, int imax,
if (level == FINEST_LEVEL) setBoundaryCondition(p, imax, jmax);
// post-smoothing
for (int i = 0; i < 5; i++) {
res = smooth(s, p, rhs, level, imax, jmax);
for (int i = 0; i < s->postsmooth; i++) {
smooth(s, p, rhs, level, imax, jmax);
if (level == FINEST_LEVEL) setBoundaryCondition(p, imax, jmax);
}
@ -154,6 +185,8 @@ void initSolver(Solver* s, Discretization* d, Parameter* p)
s->itermax = p->itermax;
s->levels = p->levels;
s->grid = &d->grid;
s->presmooth = p->presmooth;
s->postsmooth = p->postsmooth;
int imax = s->grid->imax;
int jmax = s->grid->jmax;

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@ -18,6 +18,7 @@ typedef struct {
int itermax;
int levels;
double **r, **e;
int presmooth, postsmooth;
} Solver;
extern void initSolver(Solver*, Discretization*, Parameter*);