Filtered two‐fluid models for fluidized gas‐particle suspensions

Starting from a kinetic theory based two‐fluid model for gas‐particle flows, we first construct filtered two‐fluid model equations that average over small scale inhomogeneities that we do not wish to resolve in numerical simulations. We then outline a procedure to extract constitutive models for these filtered two‐fluid models through highly resolved simulations of the kinetic theory based model equations in periodic domains. Two‐ and three‐dimensional simulations show that the closure relations for the filtered two‐fluid models manifest a definite and systematic dependence on the filter size. Linear stability analysis of the filtered two‐fluid model equations reveals that filtering does indeed remove small scale structures that are afforded by the microscopic two‐fluid model.