Numerical simulation on void formation and migration using Stokes-Brinkman coupling with effective dual-scale fibrous porous media

Abstract

Stokes-Brinkman coupling with the optimal characteristic parameters is applied to evaluate void formation and migration in effective dual-scale fibrous porous media during liquid composite molding. The optimal parameters, i.e., the effective viscosity in the continuous interfacial stress condition and stress jump coefficient in the stress jump condition, are accurately characterized. A series of multiphase flow simulations have been conducted to describe the evolutions of the void formation and its migration against the flow front position of the resin. We report that the voids are formed at low tow permeabilities and small aspect ratios of the fiber tow (relatively narrow channel). The distance between two fiber tows is observed to affect the number of voids formed. Voids immerged in resin subjected to a high permeability and a large surface tension yield a large mobility. Results from the particle tracing method reveal that in the case of high permeability and large surface tension, enhanced seepage flow adjacent to the flow front is formed because of the fountain flow nature and the bubble pushing mechanism, from which the voids in these cases migrate faster and therefore can easily escape from the resin.