Single Drop Impacts of Complex Fluids: A Review - Drops and Bubbles in Contact with Solid Surfaces - page 267

Single Drop Impacts of Complex Fluids: A Review

V. Bertola a and M. Marengo b

a

University of Liverpool, School of Engineering, Brownlow Hill, Liverpool L69 3GH, UK

b

Università degli Studi di Bergamo, Dipartimento di ingegneria Industriale Viale Marconi 5,
24044 Dalmine (BG), Italy

Abstract
The present review deals with the impact of drops of fluids with complex microstructure (non-Newtonian)
on solid surfaces, with the aim to highlight a number of relevant differences with respect to the impact
of drops of Newtonian liquids. Attention is focused on shear-thinning fluids, viscoplastic (or yield-stress)
fluids, and viscoelastic fluids, in particular dilute polymer solutions.

Contents

A. Introduction ............................................... 267

B.Impactofpower-lawdrops]Power-LawDrops ............................ 269

C.ImpactofYield-StressDrops ..................................... 272

D.ImpactofViscoelasticDrops...................................... 277

D.1. Impact on Homo-Thermal, Hydrophobic Surfaces ...................... 277

D.2. Impact on heated surfaces]Heated Surfaces . . . ....................... 283

Appendix. constitutive models]Constitutive Models for Non-Newtonian Fluids . ........... 289

A1.1.power-lawfluids]Power-LawFluids.............................. 289

A1.2.yield-stressfluids]Yield-StressFluids ............................. 290

A1.3.ViscoelasticFluids ....................................... 292

E.References................................................ 294

A. Introduction

Drop impact phenomena have attracted the interests of scientists and engineers for
more than one century [1-3], both because of their complex physical mechanisms
and because they have a very large number of applications of practical relevance.
Examples are inkjet printing, internal combustion engines, aerosol drug delivery,
distribution of agrochemicals, and of course all spray applications, which are ubiq-
uitous in industrial as well as in domestic processes, from painting or cleaning
surfaces to spray cooling and firefighting.