A Fully Coupled and Implicit Formulation for Multiphase Flow Computations

Övrigt konferensbidrag, 2007

This contribution focusses on the implementation and validation of fully coupled finite volume CFD solver, MultiFlow. This code employs momentum weighted interpolation to determine analytical expressions for the cell face velocities which are employed in the multiphase continuity equation in a collocated variable arrangement. A special approach is adopted for the momentum weighted interpolation to handle large source terms, volume fractions, and gradients of these. The resulting linearized equations are solved in a fully coupled manner. Although a number of multiphase flow models are present in MultiFlow, emphasis in this contribution is given to a distributed force immersed boundary (IB) method and a fully implicit mirroring IB method. The first method represents the presence of a body in a flow by distributed forces, and the latter method imposes the effect of an immersed body on the flow by directly modifying the Navier-Stokes coefficients obtained from its discretization. The application of the coefficients obtain the desirable boundary condition at the first time-step iteration. Details of implementation and results of numerical simulation of the fluid flow around spheres using a very simple Cartesian grid are presented. Both methods show excellent results compared to experimental data found in the literature.