# Rhie and Chow Pressure Velocity Coupling

In a collocated grid, which velocity is used in the convective term in the momentum equation? Is the Rhie and Chow constructed face velocity or an average of the adjacent cell center values(in a structured grid) used?

• Both: the Rhie & Chow velocity in the mass flux $m=\rho \mathbf{v} \cdot \mathbf{n}$ multiplied by the velocity $\mathbf{v}$ typically obtained from a flux-limiter scheme (MUSCL, MINMOD, ...) – chris Feb 9 '17 at 11:04
• If you do not use the Rhie and Chow velocity in the momentum equation, can you still get the right solution? How does the choice of the velocity affect the order of the solution or the solution itself? – Discrete_Reynolds Feb 9 '17 at 12:38
• If you do not use the Rhie and Chow velocity in the momentum equation, the momentum equation will not feel the effect of the pressure correctly. It is important to note that it is the Rhie and Chow velocity (the mass fluxes at the faces) that conserves mass. The velocity at the centroid of the cells is the one conserving momentum. – BlaB Feb 10 '17 at 14:10