Analysis of concentration distribution in gas centrifuges using finite element method.

So far, the diffusion phenomena in a gas centrifuge has been analyzed solving the governing equations by analytical approximation methods, or by numerical calculation with the finite difference method (FDM). In the present paper, a numerical procedure using the finite element method (FEM) is presented for the estimation of concentration distribution in a gas centrifuge.First, a variational form is shown for the convection-diffusion equation and its boundary conditions including concentration-, pressure- and thermal-diffusions.Next, boundary conditions are discussed especially for the ports for feed, product and waste, and accordingly we clarify a necessary condition for boundary conditions adopted in the previous analysis by FDM.Furthermore, an arbitrary pattern of the internal flow can be expressed by introducing the stream function so that the mass balance in each element is strictly attained.Computations are made on various types of gas centrifuges by assuming a simple flow pattern. The results of the present method are compared with the FDM proposed by T. Kai and provide a good agreement.