boundary condition
 

Hello,
PLease can you tell me how to set the boundary condition (vartical adiabatic walls) using finite volume method, upwind scheme;
I wrote it like this:
AAU=(0.5*dYi*(3.*t[NY][i]-4*t[NY-1][i]+t[NY-2][i]));
AAL=(0.5*dYi*(-3.*t[0][i]+4*t[1][i]-t[2][i]));
but I don't how to set it at zero???????????