Momentum and Mass Fluxes in a Gas Confined between Periodically   Structured Surfaces at Different Temperatures
  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. 
A. A. Donkov, Sudarshan Tiwari, Tengfei Liang, Steffen Hardt, Axel   Klar, Wenjing Ye
physics.flu-dyn