Study and evaluation of applied assumptions on the analytical solution of gas flow field differential equations under high velocity centrifugal force by comparing with the numerical solution using the CFD-approach

Practical employment of high angular velocity-centrifugal force field in nuclear industry, especially in separation of heavy isotopes in both industrial scale fuel production and laboratory practices, is obvious. Thermo-hydraulic differential equations of such a flow field due to ultra-high swirl velocity and also high compressibility of low mass content of gas injected into the system are very complicated and closely coupled. Thus, the analytical solution of these equations necessitates making a few assumptions. In this study, the numerical solution are conducted by the CFD approach and the finite volume method is used to evaluate assumptions of the analytical solution and to survey effects of removing these assumptions on the main variables of flow field. For this purpose, among available analytical methods to solve the governing equation, the one with the least possible assumptions is employed. The most important points in the procedure of conducting this solution are studied from the basic equations to the end and on this basis the assumptions are gathered under four titles. Then, the procedure of testing these assumptions in the FLUENT software is presented, which necessitates programming. Then the results are compared and validate by the results of the analytical method. In the next step, on the basis of consecutive elimination of the four assumptions, four different modes are defined. The novel and meaningful results obtained from the comparison of these four modes is the main incentive to present this article. This investigation, in addition to prove significant capabilities of the CFD approach for simulating this complicated flow field, clearly showed the reason of the long-term tendency toward this analytical analysis, despite its basic simplifying assumptions. Especially, with regard to the axial mass velocity due to contradictory and eliminating effect of consisting parameters.