Dear all, could someone explain to me the odd even decoupling problem? What it is When it can be found (compressible, incompressible) On which grids Is lumping the only solution? Thank you Al

ODD-EVEN DECOUPLING is seen for pressure solution in incompressible flows. This is a numerical issue caused by the way derivatives are computed say on a finite difference grid where pressure and velocities are calculated at grid nodes. You can read more about it in the book "Numerical Heat Transfer" by SV Patankar. To avoid this one usually uses a staggared grid where velocites are defined on cell faces and pressure at the cell center.