Validation studies on filtered model equations for gas-particle flows in risers

In our prior studies ([ Igci, Y., AIChE J., 2008, 54, 1431-1448 ] and [ Igci, Y.,Sundaresan, S., AIChE J., 2010, in press ]) we presented a methodology where computational results obtained through highly resolved simulations of a given microscopic two-fluid model (TFM) for gas-particle flows are filtered to deduce constitutive models for the residual correlations appearing in the corresponding filtered TFM equations that are appropriate for coarse-grid simulations of gas-particle flows. We had also analyzed the flow behavior in the vicinity of solid boundaries and proposed wall corrections for these constitutive models. We had ascertained that the filtered models do yield nearly the same time-averaged macroscale flow behavior in vertical channel flows as the underlying kinetic-theory-based TFM, thus verifying the filtered model approach. In the present study, we have performed a set of 3D computational simulations for validation of the filtered TFM against the experimental data on riser flow [ Karri, S., PSRI Challenge Problem 1, Workshop 3 Modeling Test, at the 8th International Conference on Fluidization, Tour, France, 1995 ]. It is found that inclusion of wall corrections brings the filtered model predictions closer to the experimental data and that simulations corresponding to different filter lengths yield nearly the same results.