%if(myBC == 1)
%T(1,:) = T(2,:); T(Ny,:) = T(Ny-1,:); 
%T(iny,1)= 2*Tleft - T(iny,2); T(iny,Nx)=2*Tright - T(iny,Nx-1);
%elseif(myBC == 4)

% constant inlet, constant walls, zero-gradient outlet
%T(1,:) = 2*Ttop - T(2,:); T(Ny,:) = 2*Tbot - T(Ny-1,:); 
T(iny,1)= 2*Tleft - T(iny,2); T(iny,Nx)= T(iny,Nx-1);
 
T = (S.Mask).*T + (1-S.Mask).*Thot;

%end