## top face (free)
xv(1,:) = xv(2,:);
yv(1,:) = yv(2,:);
## right face (free)
xv(:,gridres) = xv(:,gridres-1);
yv(:,gridres) = yv(:,gridres-1);
## left face (inlet)
xv(:,1) = 1;
yv(:,1) = 0;
## bottom face (wall)
xv(gridres,:) = 0;
yv(gridres,:) = 0;
