Author(s)

R. G. M. van der Sman & G. Brans

Abstract

Subgrid particle method for porous media and suspension flow R. G. M. van der Sman & G. Brans Food and Bioprocess Engineering, Wageningen University, The Netherlands Abstract In this contribution we report on the initial steps in the development of a numerical scheme for flow through packed or suspended spheres. The spheres are semiresolved, meaning that their diameter is smaller than the grid spacing, but their excluded volume is taken into account. Flow in the fluid phase is solved using the volume-averaged equations. Particle motion is solved via Newtons law, taking into account drag force and lubrication forces only. Despite the low resolution of the flow field, the particle trajectories of two spheres colliding in shear flow can be reasonable reproduced. Keywords: Lattice Boltzmann, porous media, suspension flow, Euler-Lagrangian. 1 Subgrid particle method The subgrid particle method is a Euler-Lagrangian method for modeling the multiphase flow problem of gas fluidised beds, cf. [1–3]. Here particles are underresolved, meaning that their radius is smaller than the grid spacing, but their volume is excluded for the fluid. In this paper we present an extension of the subgrid particle method towards suspension flow, requiring that hydrodynamic interactions mediated via the liquid has to be included. Such a scheme for suspensions has been proposed by Schwarzer [4], but has been implemented in 2D. The model presented in this paper is 3D, and is implemented in Lattice Boltzmann. Lattice Boltzmann is chosen as it has shown to be a very versatile method capable of simulating a variety of complex fluids. Next to suspensions and fluidized beds, the subgrid particle method can also be applied to porous media. Governing equations for porous media flow and fluidized bed are identical if solid phase is assumed immobile.

Keywords

Lattice Boltzmann, porous media, suspension flow, Euler-Lagrangian.