Changes between Initial Version and Version 1 of cypress/Programming/HeatMassTransfer/ex22.c

Timestamp:

05/14/15 15:23:10 (9 years ago)

Author:

cmaggio

Comment:

migrated content from ccs wiki

cypress/Programming/HeatMassTransfer/ex22.c

@@ +1 @@
+= Ex22.c =
+{{{#!C
+/*
+  Large Scale Computing
+  2D Heat/Mass Transfer
+  Ex22.c : Numerical Analysis
+  Solve for
+  d2c/dx2 + d2c/dy2 + 1 = 0
+  With the boundary conditions of c = 0 
+  along lines of x=1,-1, and y=1, and -1
+ 
+ */
+#include<stdio.h>
+#include<stdlib.h>
+#include<math.h>
+#include"cg.h"
+ 
+#define NUM 100  /* number of points for x and y*/
+#define TOL 1.0e-12  /* convergence tolerance */
+#define FAC 1.0e+5 /* Large factor */
+ 
+int main(void ){
+  int i,j,k,n;
+  int iw,ie,is,in;
+  double x,y,dx;
+  double phi[NUM * NUM]; /* define 1D array of length NUM * NUM */
+  double rhs[NUM * NUM]; /* define 1D array of length NUM * NUM */
+  double nzval[5 * NUM * NUM]; /* non-zero elements of A */
+  int colind[5 * NUM * NUM]; /* column indices of nonzeros */
+  int rowptr[NUM * NUM + 1]; /**/
+  int nnz;
+  FILE *fp;
+ 
+  /*assuming dx = dy : domain is 2x2 */
+  dx = 2.0 / (double)(NUM - 1);
+ 
+  /* initial & boundary conditions */
+  for (n = 0 ; n < NUM * NUM ; n++){
+    phi[n] = 0.0;
+  }
+ 
+  /* Setup Matrix A and RHS */
+  nnz = 0;
+  for (n = 0 ; n < NUM * NUM ; n++){
+    /* set general RHS */
+    rhs[n] = -dx * dx;
+ 
+    /* set first nonzero column of row index(i,j) */
+    rowptr[n] = nnz;
+ 
+    ie = n + 1;
+    iw = n - 1;
+    in = n + NUM;
+    is = n - NUM;
+ 
+    /* sounth */
+    if (is >= 0){
+      nzval[nnz] = 1.0;
+      colind[nnz] = is;
+      nnz++;
+    }     
+ 
+    /* west */
+    if (iw >= 0){
+      nzval[nnz] = 1.0;
+      colind[nnz] = iw;
+      nnz++;
+    } 
+ 
+    /* diagonal Element */
+    nzval[nnz] = -4.0;
+    colind[nnz] = n;
+    nnz++;
+ 
+    /* east */
+    if (ie < NUM * NUM){
+      nzval[nnz] = 1.0;
+      colind[nnz] = ie;
+      nnz++;
+    } 
+ 
+    /* north */
+    if (in < NUM * NUM){
+      nzval[nnz] = 1.0;
+      colind[nnz] = in;
+      nnz++;
+    } 
+  }
+  rowptr[NUM * NUM] = nnz;
+ 
+ 
+  /* Setting Boundary Conditions */
+  /* Add Big Number to Both Sides */
+  for (i = 0 ; i < NUM ; i++){
+    /* Bottom */
+    n = i;
+    for (k = rowptr[n] ; k < rowptr[n+1] ; k++){
+      if (n == colind[k]){
+        nzval[k] += FAC;
+        rhs[n] += FAC * phi[n];
+      }
+    }
+    /* Top */
+    n = i + NUM * (NUM - 1);
+    for (k = rowptr[n] ; k < rowptr[n+1] ; k++){
+      if (n == colind[k]){
+        nzval[k] += FAC;
+        rhs[n] += FAC * phi[n];
+      }
+    }
+  }
+  for (j = 0 ; j < NUM ; j++){
+    /* Left */
+    n = j * NUM;
+    for (k = rowptr[n] ; k < rowptr[n+1] ; k++){
+      if (n == colind[k]){
+        nzval[k] += FAC;
+        rhs[n] += FAC * phi[n];
+      }
+    }
+    /* Right */
+    n = NUM - 1 + j * NUM;
+    for (k = rowptr[n] ; k < rowptr[n+1] ; k++){
+      if (n == colind[k]){
+        nzval[k] += FAC;
+        rhs[n] += FAC * phi[n];
+      }
+    }
+  }
+ 
+ 
+  /* solve with CG */
+  k = solve_cg(NUM * NUM, nnz, nzval, colind, rowptr, phi, rhs, TOL);
+  if (k < 0){
+    printf("calculation failed\n");
+    exit(-1);
+  }
+  printf("Number of Interation=%d\n",k);
+ 
+ 
+  /* Output Result */
+  fp = fopen("res.dat","w");
+  if (fp == NULL){
+    printf("File could not create\n");
+    exit(-1);
+  }
+ 
+  for (i = 0 ;i < NUM ; i++){
+    for (j = 0 ; j < NUM ; j++){
+      x = -1.0 + 2.0 * (double)i / (double)(NUM - 1);
+      y = -1.0 + 2.0 * (double)j / (double)(NUM - 1);
+      fprintf(fp,"%e %e %e\n",x,y,phi[i + NUM * j]);
+    }
+  }
+  fclose(fp);
+ 
+  printf("Done\n");
+}
+}}}