Changhai Chen

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


The problem of steady thermocapillary convection in cavities and liquid layers in the absence of gravity is studied. The flow is driven by a temperature gradient parallel to the interface.;An effective algorithm for analysis of the above problem has been developed. The algorithm is based on a coordinate transformation method, streamfunction vorticity formulation, and second-order finite-difference discretization. The unknown physical domain is mapped onto a rectangular computational domain, with the explicit form of the mapping function not being known. The field variables and the mapping function are determined simultaneously using Picard-type iteration. The numerical experiments indicate that the algorithm delivers the second-order accuracy even for very large interfacial distortion.;The question of existence of nonisothermal interfaces has been investigated. It is demonstrated that the external temperature has to satisfy constraint conditions in order for a nonisothermal interface to exist in a continuous form.;Extensive numerical parameter studies show that the dominant response of the flow system consists of a large interfacial distortion and not just a pure convection as commonly assumed. This is consistent with the analytical results describing conditions guaranteeing existence of a nonisothermal interface.;The nonunique steady solutions have been found to exist at very low Reynolds and capillary numbers. The primary bifurcation point appears to be supercritical. The response of the system is very sensitive with respect to the functional form of the external heating, variations of transport parameters, such as Reynolds and capillary numbers, and geometrical constraints, such as length of the cavity and the type of contact conditions.;Double liquid layer systems have been studied in order to assess potential of the encapsulation technique for control of the thermocapillary convection. A detailed analysis of the flow and temperature fields has been carried out. The results show that the thermocapillary convection can be controlled by properly selecting the properties of the encapsulating liquid.



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