DYNAMICS OF DROPS IN BRANCHED TUBES

The flow of two-dimensional deformable drops through branching (bifurc ating) tubes is studied numerically using a boundary integral formulat ion. The undeformed drop diameter is assumed to be less than the tube diameter. Capillary numbers between 10(-2) and 1 are considered. Flow in the branching tube is characterized by the fraction of fluid which enters each of the two downstream branches. The likelihood of drops en tering the high-flow-rate branch increases as (i) the viscosity ratio between the drops and suspending fluid decreases, (ii) the capillary n umber increases, and (iii) the drop size increases. Hydrodynamic inter actions between the suspended drops increase the number of drops which enter the low-flow-rate branch. The implications of these results for dispersion processes and local transport are explored. The disturbanc e flow created by drops passing over 'dead-end' pores or cavities resu lts in fluid transfer between the pore and the free stream; suspension s may then be effective in improving the 'cleaning' of porous material s.