Patterning surface textured plates with a viscoplastic fluid

TL;DR

This study demonstrates how designing specific macroscopic patterns on substrates can precisely control the shape of viscoplastic fluid deposits, independent of adhesion forces, using experiments in a lifted Hele-Shaw cell.

Contribution

It introduces a novel method for controlling viscoplastic fluid deposition through substrate patterning, expanding beyond traditional approaches based on plate separation.

Findings

Substrate patterns determine the final footprint shape of the viscoplastic fluid.

Pattern design has minimal impact on the normal adhesive force.

Different shapes like slots, squares, pyramids, and triangles influence fluid dynamics.

Abstract

The deposition of a viscoplastic fluid onto a substrate can be achieved by simply moving apart two plates initially separated by a fluid filled gap, where the footprint shape depends on the initiation of a fingering instability. Here, we present another approach for the controlled deposition of a viscoplastic fluid by designing the macroscopic structures of the solid substrate. Through experiments in a lifted Hele-Shaw cell, we explore how slot, square, pyramid, and triangle-shaped patterns affect the dynamics of liquid deposition. These substrate structures directly control the final shape of the viscoplastic fluid footprint. It turns out that these substrate patterns have little influence on the normal adhesive force acting on the plates.