title: Variational scheme towards an optimal lifting drive in fluid adhesion.
abstract: One way of determining the adhesive strength of liquids is provided by a probe-tack test, which measures the force or energy required to pull apart two parallel flat plates separated by a thin fluid film. The vast majority of the existing theoretical and experimental works in fluid adhesion use very viscous fluids, and consider a linear drive L(t)∼Vt with constant lifting plate velocity V. This implies a given energy cost and large lifting force magnitude. One challenging question in this field pertains to what would be the optimal time-dependent drive Lopt(t) for which the adhesion energy would be minimized. We use a variational scheme to systematically search for such Lopt(t). By employing an optimal lifting drive, in addition to saving energy, we verify a significant decrease in the adhesion force peak. The effectiveness of the proposed lifting procedure is checked for both Newtonian and power-law fluids.
authors.affiliation: Departamento de Física, Universidade Federal de Pernambuco, Recife PE 50670-901, Brazil.
authors.forename: Eduardo O
authors.initials: EO
authors.lastname: Dias
authors.forename: José A
authors.initials: JA
authors.lastname: Miranda