On the hydrodynamic permeability of foamlike media

[摘要] This work entails the improvement of an existing three dimensional pore-scale model.Stagnant zones are included, the closure of the volume averaged pressure gradient is improvedand an improved calculation of pore-scale averages, using the RUC, is done for themodel to be a more realistic representative of the REV and thus of the foamlike material.Both the Darcy and the Forchheimer regimes are modelled and a general momentumtransport equation is derived by means of an asymptotic matching technique. The RUCmodel is also extended to cover non-Newtonian flow. Since metallic foams are generallyof porosities greater than 90%, emphasis is put on the accurate prediction of permeabilityfor these porosities. In order to improve permeability predictions for these high porositycases an adaptation to the RUC model was considered, whereby rectangular prisms werereplaced by cylinders. Although this adaptation appears to give more accurate permeabilitiesat very high porosities, its implementation in a generalised model seems impractical.The prediction of the characteristic RUC side length is discussed and results of both thecylindrical strand model and the square strand model are compared to experimental work.

[发布机构] Stellenbosch University