Deformation And Spreading Of An InviscidDrop Impinging On A Solid Surface

Abstract

Axisymmetric spreading of an idealised inviscid liquid drop impinging on a horizontal solid surface is analysed (including surface tension) using a Boundary Integral Method for selected Weber numbers ( We — 10, 20, 50, 100 based on initial drop radius and impact velocity). Progressive accumulation of liquid in a rim around the periphery of the spreading inviscid drop is predicted except when We = 100 for which no such rim is predicted. It is concluded that the experimentally observed rim is due solely to viscous retardation at this higher Weber number. The calculated reduction in drop height with time is found to be almost independent of Weber number, and agrees extremely well with experimental data despite the absence of viscous effects in the calculations. The effect of viscosity is explored by comparing the calculated and measured spreading rates for two experiments. The viscous reduction in the radius of spreading during most of the primary deformation is predicted to be approximately linear in time.