Patterned Heating Induced Propulsion
Abstract
This study explores propulsion effects generated by patterned heating acting on smooth and corrugated surfaces. The model problem assumes that the upper plate moves freely, and the lower plate is stationary, equipped with grooves, and exposed to spatially distributed heating. Our findings identify two distinct propulsion effects: thermal streaming and thermal drift. Thermal streaming occurs when given sufficient heating intensity with net flow in the left or right direction characterized by a pitchfork bifurcation. The efficiency of this technique can be controlled using the wavelength of heating. Thermal drift represents a pattern interaction effect. Its strength depends on the relative positions of the heating and groove patterns and is most significant when the groove peaks and surface hot spots are quarter wavelengths apart. Changing the heating pattern position relative to grooves permits a change of direction of the propulsive effect. Strengths of propulsive effects increase with a reduction of Prandtl number and with the addition of a uniform heating component.