Diffusioosmotic corner flows

TL;DR

This paper derives an exact analytical solution for diffusioosmotic flows in a corner geometry, revealing steady eddies and providing insights for microscale mixing and benchmarks for simulations.

Contribution

It introduces a novel analytical approach to model diffusioosmotic flows in corners, linking chemical activity to flow patterns with explicit solutions.

Findings

Steady eddies can form in chemically active corners.

Closed-form expressions clarify flow mechanisms.

Results aid design of microfluidic mixing strategies.

Abstract

We study flows generated within a two-dimensional corner by the chemical activity of the confining boundaries. Catalytic reactions at the surfaces induce diffusioosmotic motion of the viscous fluid throughout the domain. The presence of chemically active sectors can give rise to steady eddies reminiscent of classical Moffatt vortices, which are mechanically induced in similar confined geometries. In our approach, an exact analytical solution of the diffusion problem in a wedge geometry is derived and coupled to the diffusioosmotic slip-velocity formulation, yielding the stream function of associated Stokes flow. In selected limiting cases, simple closed-form expressions provide clear physical insight into the underlying mechanisms. Our results open new perspectives for the design of microscale mixing strategies in dead-end pores and cornered microfluidic channels, and offer benchmarks for numerical simulations of confined (diffusio)osmotic systems.