Sir, I had tried with different courant Number starting from 1 with the first order and second order upwind but in both the case the y and z velocity is not converging. I attaching the graph below. This is generated with second order upwind and courant 1 and if I use first order upwind then those oscillation are minimized and gives a smooth graph but still the y and z velocity not converging with explicit spatial and transient formulation and even residuals did not go below 10^ (-1). nCan anyone tell me where I had done a mistake or what I have to do for convergence??n