The gradient of the solution variables are required in order to evaluate diffusive fluxes, velocity derivatives, and for higher-order discretization schemes by the solver. The gradients of solution variables at cell centers can be determined using three approaches: –Green-Gauss Cell-Based – Good, but solution may have false diffusion (smearing of the solution fields) –Green-Gauss Node-Based – More accurate; minimizes false diffusion; (strongly recommended for tri/tet and hybrid meshes) –Least-Squares Cell-Based – The default method. Less expensive to compute than Node-Based gradients. Slightly more expensive than Cell-Based gradients. However, exactly reconstruct linear field on highly skewed or distorted meshes. (appropriate for any kind of meshes)