【旧代码】传热过程数值模拟

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/* * 等温边界 */ #include<iostream> #include<cmath> using namespace std; const double out_temp=30.0;//外边界温度 const double in_temp=0.0;//内边界温度 const double accuracy=0.00000001;//精度 const double lambda=0.53;//导热系数 const int width=15;//上部点阵宽度 const int width_bottom=4;//下部点阵宽度 const int height=4;//上部点阵高度 const int height_bottom=7;//下部点阵高度 /* //另一组参数 const int width=16; const int width_bottom=6; const int height=6; const int height_bottom=6; */ //总共点数 const int num_of_points=width*height+width_bottom*height_bottom; //单个点 class point { public: double temp;//温度 int up;//数组下标 int down; int left; int right; point(){ temp=0.0;//初始化成0摄氏度 up=down=right=left=0; } }; ostream & operator<<(ostream & src_stream,const point & src){ src_stream<<"temp="<<src.temp; src_stream<<" up="<<src.up<<" down="<<src.down; src_stream<<" left="<<src.left<<" right="<<src.right; return src_stream; } void print_grid(point * points){//输出网格各点的温度 cout<<endl; for(int position=0;position>=0;position=points[position].down){ for(int tmp=position;tmp>=0;tmp=points[tmp].right){ cout.width(10); cout<<points[tmp].temp; } cout<<endl<<endl<<endl<<endl; } } double calc_direction(point * points,int direction,double &opposit_weight){ //计算给定方向邻点的温度和反方向的权重。 switch (direction) { case -1: return out_temp; break; case -2: return in_temp; break; case -3: opposit_weight*=2; return 0.0; break; default: return points[direction].temp; } } void compu_point(point * points,int now){ //根据周围四个点算出指定点的温度 double left_temp; double right_temp; double up_temp; double down_temp; double up_wight=0.25;//上方权重,默认0.25 double down_wight=0.25; double left_wight=0.25; double right_wight=0.25; left_temp=calc_direction(points,points[now].left,right_wight); right_temp=calc_direction(points,points[now].right,left_wight); up_temp=calc_direction(points,points[now].up,down_wight); down_temp=calc_direction(points,points[now].down,up_wight); points[now].temp=left_temp*left_wight+right_temp*right_wight+up_temp*up_wight+down_temp*down_wight; } void rec_walk(point * points){ // "左=>右"里嵌"上=>下"遍历计算 for(int position=0;position>=0;position=points[position].right) for(int tmp=position;tmp>=0;tmp=points[tmp].down) compu_point(points,tmp); } void heat_rate(point * points){ //计算导热量 double out_sum=0.0; double in_sum=0.0; //外边界 int pos=0; double tmp=0.0; for(;points[pos].right>=0;pos=points[pos].right){ tmp=out_temp - points[pos].temp ; if(points[pos].right<=0) out_sum += 0.5*tmp; else out_sum+=tmp; } for(pos=points[0].down;points[pos].down>=0;pos=points[pos].down){ tmp=out_temp - points[pos].temp ; if(points[pos].down<=0) out_sum += 0.5*tmp; else out_sum+=tmp; } //内边界 for(pos=num_of_points-1;points[pos].right<0;pos=points[pos].up){ tmp = points[pos].temp - in_temp ; if(points[pos].down<=0) in_sum += 0.5*tmp; else in_sum +=tmp; } for(pos=points[pos].right;points[pos].right>=0;pos=points[pos].right){ tmp = points[pos].temp - in_temp; if(points[pos].right<=0) in_sum += 0.5*tmp; else in_sum += tmp; } out_sum*=lambda; in_sum*=lambda; cout<<"外边界导热量="<<out_sum; cout<<"\n内边界导热量="<<in_sum; cout<<"\n误差="<<(in_sum-out_sum)/in_sum*100<<"%"<<endl; } void init_grid(point * points){ //初始化网格 int position=0; //初始化最上面的边 for(int i=0;i<width;i++){ points[i].up=-1;//-1表示外边界，-2内边界,-3表示绝热 points[i].left=i-1; points[i].right=i+1; points[i].down=i+width; position=i; } points[0].left=-1;//等温 points[width-1].right=-3;//绝热 //上面区域 for(int i=1;i<height;i++){ for(int j=0;j<width;j++){ points[i*width+j].up =i*width+j-width; points[i*width+j].left =i*width+j-1; points[i*width+j].right=i*width+j+1; points[i*width+j].down =i*width+j+width; position=i*width+j; } points[i*width+0].left=-1; points[i*width+width-1].right=-3; } position-=width; position++; for(int j=width_bottom;j<width;j++){ points[position+j].down =-2;//内边界 } position+=width; //下面区域 for(int i=0;i<height_bottom;i++){ for(int j=0;j<width_bottom;j++){ if(i) points[position+i*width_bottom+j].up=position+i*width_bottom+j-width_bottom; else points[position+i*width_bottom+j].up=position+i*width_bottom+j-width; points[position+i*width_bottom+j].left=position+i*width_bottom+j-1; points[position+i*width_bottom+j].right=position+i*width_bottom+j+1; points[position+i*width_bottom+j].down=position+i*width_bottom+j+width_bottom; } points[position+i*width_bottom+0].left=-1; points[position+i*width_bottom+width_bottom-1].right=-2; } //下边界 position+=width_bottom*height_bottom; position-=width_bottom; for(int j=0;j<width_bottom;j++){ points[position+j].down=-3; } position+=width_bottom; } int main(){ point * points=new point[num_of_points]; init_grid(points); //初始化完。输出看看。 //for(int i=0;i<num_of_points;i++) // cout<<i<<" => "<<points[i]<<'\n'; cout<<"初始温度分布（最外层和最内层没有显示）：\n"; print_grid(points); //开始迭代计算 double diff=out_temp; int times=0; for(;diff>out_temp*accuracy;times++){ //"上=>下" 里嵌 "左=>右"遍历计算 diff=0.0; for(int now=0;now<num_of_points;now++){ double tmp=points[now].temp; compu_point(points,now); tmp=abs(tmp-points[now].temp); diff = diff>tmp?diff:tmp; } } cout<<"\n迭代计算"<<times<<"次得到的温度分布（最外层和最内层没有显示）：\n"; print_grid(points); heat_rate(points); delete [] points; return 0; }

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/* * 对流边界 */ #include<iostream> #include<cmath> using namespace std; const double out_temp=30.0;//外边界温度 const double out_h=10.0;//外边界对流换热系数 const double in_temp=10.0;//内边界温度 const double in_h=4 .0;//内边界对流换热系数 const double accuracy=0.00000001;//精度 const double lambda=0.53;//导热系数 const int width=15;//上部点阵宽度 const int width_bottom=4;//下部点阵宽度 const int height=4;//上部点阵高度 const int height_bottom=7;//下部点阵高度 const double delta_x=3.0/(2*width+1); const double out_Bi=out_h*delta_x/lambda;//外表面网格Bi数 const double in_Bi = in_h*delta_x/lambda;//内表面网格Bi数 /* //另一组参数 const int width=150; const int width_bottom=40; const int height=40; const int height_bottom=70; */ //总共点数 const int num_of_points=width*height+width_bottom*height_bottom; //单个点 class point { public: double temp;//温度 int up;//数组下标 int down; int left; int right; point(){ temp=0.0;//初始化成0摄氏度 up=down=right=left=0; } }; ostream & operator<<(ostream & src_stream,const point & src){ src_stream<<"temp="<<src.temp; src_stream<<" up="<<src.up<<" down="<<src.down; src_stream<<" left="<<src.left<<" right="<<src.right; return src_stream; } void print_grid(point * points){//输出网格各点的温度 cout<<endl; for(int position=0;position>=0;position=points[position].down){ for(int tmp=position;tmp>=0;tmp=points[tmp].right){ cout.width(10); cout<<points[tmp].temp; } cout<<endl<<endl<<endl<<endl; } } void dump_all(point * points){//便于调试 for(int i=0;i<num_of_points;i++) cout<<i<<" => "<<points[i]<<'\n'; } double calc_direction(point * points,int direction,double &opposit_weight,double &this_weight){ //计算给定方向邻点的温度和反方向的权重。 switch (direction) { case -1://外边界 this_weight*=out_Bi; return out_temp; break; case -2://内边界 this_weight*=in_Bi; return in_temp; break; case -3://绝热 this_weight=0.0; opposit_weight*=2; return 0.0; break; default: return points[direction].temp; } } void compu_point(point * points,int now){ //根据周围四个点算出指定点的温度 double left_temp; double right_temp; double up_temp; double down_temp; double up_wight=1;//上方权重 double down_wight=1; double left_wight=1; double right_wight=1; left_temp=calc_direction(points,points[now].left,right_wight,left_wight); right_temp=calc_direction(points,points[now].right,left_wight,right_wight); up_temp=calc_direction(points,points[now].up,down_wight,up_wight); down_temp=calc_direction(points,points[now].down,up_wight,down_wight); double Bi_sum=up_wight+down_wight+right_wight+left_wight; points[now].temp=(left_temp*left_wight+right_temp*right_wight+up_temp*up_wight+down_temp*down_wight)/Bi_sum; } void rec_walk(point * points){ // "左=>右"里嵌"上=>下"遍历计算 for(int position=0;position>=0;position=points[position].right) for(int tmp=position;tmp>=0;tmp=points[tmp].down) compu_point(points,tmp); } void heat_rate(point * points){ //计算导热量 double out_sum=0.0; double in_sum=0.0; //外边界 int pos=0; double tmp=0.0; for(;points[pos].right>=0;pos=points[pos].right){ tmp=out_temp - points[pos].temp ; if(points[pos].right<=0) out_sum += 0.5*tmp; else out_sum+=tmp; } for(pos=points[0].down;points[pos].down>=0;pos=points[pos].down){ tmp=out_temp - points[pos].temp ; if(points[pos].down<=0) out_sum += 0.5*tmp; else out_sum+=tmp; } //内边界 for(pos=num_of_points-1;points[pos].right<0;pos=points[pos].up){ tmp = points[pos].temp - in_temp ; if(points[pos].down<=0) in_sum += 0.5*tmp; else in_sum +=tmp; } for(pos=points[pos].right;points[pos].right>=0;pos=points[pos].right){ tmp = points[pos].temp - in_temp; if(points[pos].right<=0) in_sum += 0.5*tmp; else in_sum += tmp; } out_sum*=out_h*delta_x; in_sum *=in_h *delta_x; cout<<"外边界导热量="<<out_sum; cout<<"\n内边界导热量="<<in_sum; cout<<"\n误差="<<(in_sum-out_sum)/in_sum*100<<"%"<<endl; } void init_grid(point * points){ //初始化网格 int position=0; //初始化最上面的边 for(int i=0;i<width;i++){ points[i].up=-1;//-1表示外边界，-2内边界,-3表示绝热 points[i].left=i-1; points[i].right=i+1; points[i].down=i+width; position=i; } points[0].left=-1;//对流 points[width-1].right=-3;//绝热 //上面区域 for(int i=1;i<height;i++){ for(int j=0;j<width;j++){ points[i*width+j].up =i*width+j-width; points[i*width+j].left =i*width+j-1; points[i*width+j].right=i*width+j+1; points[i*width+j].down =i*width+j+width; position=i*width+j; } points[i*width+0].left=-1; points[i*width+width-1].right=-3; } position-=width; position++; for(int j=width_bottom;j<width;j++){ points[position+j].down =-2;//内边界 } position+=width; //下面区域 for(int i=0;i<height_bottom;i++){ for(int j=0;j<width_bottom;j++){ if(i) points[position+i*width_bottom+j].up=position+i*width_bottom+j-width_bottom; else points[position+i*width_bottom+j].up=position+i*width_bottom+j-width; points[position+i*width_bottom+j].left=position+i*width_bottom+j-1; points[position+i*width_bottom+j].right=position+i*width_bottom+j+1; points[position+i*width_bottom+j].down=position+i*width_bottom+j+width_bottom; } points[position+i*width_bottom+0].left=-1; points[position+i*width_bottom+width_bottom-1].right=-2; } //下边界 position+=width_bottom*height_bottom; position-=width_bottom; for(int j=0;j<width_bottom;j++){ points[position+j].down=-3; } position+=width_bottom; } int main(){ point * points=new point[num_of_points]; init_grid(points); //dump_all(points); cout<<"初始温度分布（最外层和最内层没有显示）：\n"; print_grid(points); //开始迭代计算 double diff=out_temp; int times=0; for(;diff>out_temp*accuracy;times++){ //"上=>下" 里嵌 "左=>右"遍历计算 diff=0.0; for(int now=0;now<num_of_points;now++){ double tmp=points[now].temp; compu_point(points,now); tmp=abs(tmp-points[now].temp); diff = diff>tmp?diff:tmp; } } cout<<"\n迭代计算"<<times<<"次得到的温度分布（最外层和最内层没有显示）：\n"; print_grid(points); heat_rate(points); delete [] points; return 0; }