Can u give a c++ code to calculate flux over 2D grids please

please can u help me to solve posted problem

I wanted to calculate outgoing flux on 2D circular grid. So first part of this code is for to get grid point after that i initializes variables on those grid points, now i want to calculate diagonal to get unit normal through it . above code running upto global time step

I am writing cfd code taking reference of FORTRAN code following is the code which i had written but this program is not running #include #include #include //#include "constant1.h" using namespace std; float radi=11,rado=59.99,dro; float r=11,spar=0.9415,pi=3.141592654,cfl=0.50,wn=2*pi*0.6/radi; int i=1,ni=200,nj=50,nth=ni,nrad=nj,ncon1=0,ncon2=0,ncon=1000,lod=3,lexp=2,eps=0; //float wn; static int j=1; class project { public: float x,y,r,th; void grid() { fstream infile("grid11.dat",ios::out); for(r=11;r<=60;r++) { for(th=0; th<=2*pi; th=th+((pi/100)+(.00025*pi/98))) { cout<

i have to calculate diagonal using grid points

I want to covert following program into c++ subroutine gstep common/blk1/u(3,800,800),fnl(3,800,800),gnl(3,800,800) common/blk2/ni,nj,radi,rado,dt,cfl,lod,dto,wn,wl,lexp,dtot,ndiv,pi,phi c in case a global time step is reqd. eg. time accurate problems em=1. ep=1. c=1/sqrt(ep*em) dt=10000. cl=ar/diag do i=1,ni do j=4,nj-3 call grid(i,j,x1,y1,x2,y2,x3,y3,x4,y4,xp1,yp1,ar,c,0) diag=0.5*(sqrt((x1-x3)**2+(y1-y3)**2)+sqrt((x2-x4)**2 * +(y2-y4)**2)) cl=ar/diag dtemp=cfl*cl/(c) if(dtemp.lt.dt)then dt=dtemp endif enddo enddo wl=2*pi/wn write(*,*) wn,wl,dt ndiv=wl/(c*dt) write(*,*) ndiv ndiv=ndiv+1 dt=wl/(c*(ndiv)) write(*,*) ndiv,dt return end