Critical comparison of the different versions of the OpenFOAM on the simulation of spillway
The results of numerical simulation for a two-phase flow of two incompressible and immiscible liquids through a trapezoidal spillway are presented. To simulate the free boundary, we used the method of fluid volume. The aim of the work was to demonstrate the capabilities of the various versions of interFoam solver of the OpenFOAM package for modelling the considered class of flows. Numerical calculations were performed using the OpenFOAM weirOverFlow tutorial. In order to improve the consistency, usability, flexibility and ease of modifying the interFoam solver, the existing interDyMFoam solver with the local dynamic mesh adaptation function was combined with the interFoam solver with a static computational mesh. In addition, in the OpenFOAM6 package, the fvcDdtPhiCoeff coefficient used for calculating the time derivative and taking into account the Rhie- Chow correction on the collocated grid for calculating mass fluxes on the cell faces was changed in order to improve stability/accuracy and eliminate pressure oscillations at high Courant numbers. The calculation of fvcDdtPhiCoeff coefficient in OpenFOAM5 requires the density value from the current time step along with the mass flow value from the previous time step, while in OpenFOAM6, both density and mass flow values are taken from the previous time step for calculation of the fvcDdtPhiCoeff coefficient. The results of numerical calculations of the OpenFOAM6 package show that such changes lead to an excessively fast transition of the transient flow to the stationary one in comparison with other versions of the OpenFOAM package.