Hybrid numerical modeling of bellows effect in supersonic rotating flow using modified continuum solvers

The primary objective of this work is to study bellows effect in a compressible rotating isotopic flow using appropriate hybrid numerical model by focusing on evaluating continuum solvers. The hybrid numerical model will be used to analyze the bellows and operating parameters characteristics on separation power. In this regard, two coupled particle-continuum computing frameworks are developed to model supersonic flow inside a gas centrifuge machine for uranium enrichment. These approaches are intended to be more accurate than conventional fluid dynamics solutions (CFD) and more rapid than most pure molecular methods (direct simulation Monte Carlo, DSMC). This study presents a review and the performance comparison of two solvers from the open-source CFD tool OpenFOAM (R): the solver based on the rhoSimpleFoam algorithm (PISO and SIMPLE) and rhoCentralFoam which are specifically created for conducting compressible transient and utilize central-upwind schemes for convective fluxes. These are renowned for their ability to effectively balance accuracy and robustness in accurately capturing shock waves and steep gradient phenomena. In this analysis, a coupled DSMC-CFD approach is employed to integrate the modeling of particle and fluid domains to improve the computational efficiency for transitional flows that involve continuum and molecular flows. The DSMC-CFD method is developed into the OpenFOAM framework to simulate the UF6 gas flow in whole regions of a centrifuge machine. OpenFOAM allows solving the molecular region and modeling the interaction between the continuum and molecular flows. In this study, the chosen coupled method is employed to investigate the drives, including bellows and feed mechanisms, in the separation process of a gas centrifuge, as well as the separation power.