(98a) An Idea of DEM-CFD Coupling Model Decoupling Spatial Averaging Scale from Computational Cell Size

DEM-CFD coupling model is widely used for the numerical simulation of dense gas-solid flows. Because it is a mesoscopic approach, fluid motion is obtained by solving spatially-averaged continuity and momentum equations. It is usual that computational cell size used for CFD calculation is same with the spatial-averaging scale of governing equations and the results obtained by the model can change depending on the computational cell size. Fine computational cell is desired for accurate CFD calculation, on the contrary, sufficiently large averaging scale is required to fulfil the requirement of spatial averaging. These are contradictory and it is important to adopt a proper cell size carefully to obtain reasonable results. It could be a big problem in the case particles with different size exist and particle size changes over time and position.

In the present study, an idea of DEM-CFD coupling model that decouples spatial averaging scale from calculation cell size used for CFD calculation is discussed. We present the concept of proposed model first and develop discussions on its feasibility and validity.