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Thesis Format



Master of Engineering Science


Mechanical and Materials Engineering


Floryan, Jerzy M.


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.

Summary for Lay Audience

Imagine two flat surfaces, one placed over the other. The top one can move, while the bottom one is fixed, has grooves, and is heated in a specific pattern. This study investigates how these heating and groove patterns can make the top plate move by itself. The movement of the top plate is influenced by the behaviour of the fluid between the plates when the bottom plate is heated. The first way this happens is through a process called thermal streaming. This process occurs when we heat the bottom plate intensely. The fluid between the plates starts to move, similar to how water circulates in a pot when it gets hot. This fluid movement, in turn, causes the top plate to move. The second process is known as thermal drift. It happens when we align the heating patterns with the groove patterns on the bottom plate. With proper alignment, the fluid moves. This movement then causes the top plate to move as well. By adjusting this alignment, we can change the direction of the top plate’s movement and its velocity. Furthermore, we discovered that the velocity of the top plate can be increased by using a better-conducting fluid and by adding uniform heating to the lower plate. In simple terms, this study demonstrates that by manipulating the form of heating and topography of the lower plate, we can generate and control the movement of the upper plate. This finding can be used for designing innovative propulsion processes with various applications.

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.