The steady shear of three-dimensional wet polydisperse foams

In this paper, steady shear results are presented from simulations of three-dimensional, polydisperse, wet foams. The simulations use the bubble dynamics model to obtain steady shear results over a wide range of gas fractions, shear rates, and for two normal bubble size distributions. Bingham plastic behaviour is observed in all foams with gas volume fraction above the critical packing fraction of randomly packed hard spheres. Time averaged stress results are seen to be independent of the bubble size distribution. The predicted yield stress behaviour compares favourably with experimental yield stress measurements by previous authors. Shear may increase or decrease the level of topological disorder of foam depending on the foam polydispersity. The present data indicate that shear-induced topological ordering occurs because of insufficient time available for bubbles to pack efficiently in a sheared foam. (C) 2000 Elsevier Science B.V. All rights reserved.