Momentum and Mass Fluxes in a Gas Confined between Periodically Structured Surfaces at Different Temperatures

TL;DR

This paper demonstrates that structured surfaces at different temperatures can induce mass and momentum fluxes in a confined gas, revealing new mechanisms for energy conversion and thermal pumping.

Contribution

It introduces the novel finding that structured surfaces can generate fluxes orthogonal to temperature gradients, supported by analytical and numerical analysis.

Findings

Maximum momentum flux occurs in free-molecular flow regime.

Normalized mass flux peaks in transition flow regime.

Phenomena have potential applications in energy conversion and thermal pumping.

Abstract

It is well known that in a gas-filled duct or channel along which a temperature gradient is applied, a thermal creep flow is created. Here we show that a mass and momentum flux can also be induced in a gas confined between two parallel structured surfaces at different temperatures, i.e. \textit{orthogonal} to the temperature gradient. We use both analytical and numerical methods to compute the resulting fluxes. The momentum flux assumes its maximum value in the free-molecular flow regime, the (normalized) mass flux in the transition flow regime. The discovered phenomena could find applications in novel methods for energy-conversion and thermal pumping of gases.