Microscale fluid flow induced by thermoviscous expansion along a traveling wave

TL;DR

This paper investigates a novel microscale fluid flow caused by thermoviscous expansion and temperature-dependent viscosity, combining numerical, analytical, and experimental methods to understand and validate the effect.

Contribution

It introduces a new thermo-mechanical mechanism for microscale fluid flow driven by thermal expansion and viscosity changes, supported by comprehensive analysis and experimental validation.

Findings

Net fluid flow can be induced by thermal effects at microscale.

Theoretical predictions match experimental measurements.

The effect is controllable via external heating.

Abstract

The thermal expansion of a fluid combined with a temperature-dependent viscosity introduces nonlinearities in the Navier-Stokes equations unrelated to the convective momentum current. The couplings generate the possibility for net fluid flow at the microscale controlled by external heating. This novel thermo-mechanical effect is investigated for a thin fluid chamber by a numerical solution of the Navier-Stokes equations and analytically by a perturbation expansion. A demonstration experiment confirms the basic mechanism and quantitatively validates our theoretical analysis.