A NON-DARCY MODEL FOR RECIRCULATING FLOW-THROUGH A FLUID-SEDIMENT INTERFACE IN A CYLINDRICAL CONTAINER

A numerical investigation has been undertaken to characterize the axis ymmetric laminar flow generated by a rotating disk inside a cylinder w ith an open top, containing a Viscous fluid above as layer of fluid-sa turated porous medium. The mathematical model is based on a continuum approach for both fluid and porous regions. Attention is focussed on c onditions favouring steady, stable, axisymmetric solutions of the Darc y-Brinkman-Lapwood equation. The accuracy of the method is verified by solving some vortex now problems in disk-cylinder geometries and comp aring the results with: (a) existing numerical solutions and, (b) expe rimental pressure measurements in a similar geometry. Calculations are performed to investigate the fluid exchange between the porous region (porewater) and the overlying water. Results indicate that flow throu gh composite (fluid-sediment) systems can be handled with good accurac y by the method presented here. With our approach the magnitude of adv ective porewater transport in sediments may be predicted. This finding is important for improved designs of flux chambers and also for under standing advective transport phenomena.