An improved numerical scheme to evaluate the pressure gradient on unstructured meshes for two-phase flow analysis

In multi-dimensional two-phase flows, a local pressure is very important because it directly influences the phase change and it may lead to a great change in the flow field. This in turn puts emphasis on the accurate evaluation of local pressure gradient. This paper presents a new numerical scheme to evaluate the pressure gradient at cell centers on unstructured meshes for a three-dimensional thermal-hydraulic code, named CUPID. The results of the new scheme for a simple test function, a gravity-driven cavity, and a wall boiling two-phase flow are compared with those of the previous schemes in the CUPID code.