Interfacial Driven Convection - The Effect of Side Walls on Pattern Development

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ABSTRACT -- CTS-9307819 Narayanan The proposed research focuses on interfacial driven convection in stacked fluid layers. A specific goal is the study of the effect of sidewalls on the flow pattern or structure in superposed fluids. The PI expects to find the following: a) the conditions for the onset of convection in a bounded two layer system and compare our results to calculations, b) the flow pattern development in the post onset region for a bi-layer system, c) the onset conditions in a tri-layer where the physics are considerably different than a two layer system. An experiment will be conducted in circular and rectangular cylindrical containers and the multi-layer will be bounded in the vertical direction by two horizontal thermally conducting plates, one of which is transparent. The critical conditions for onset will be determined by the enhancement of heat transfer and flow visualization. A Schmidt-Milverton type of plot will be made. A detailed model of the convective flow will be compared with the experimental results. This problem is rich in physics on account of multi-layer interaction in interfacial driven or Marangoni-B nard convection. This interaction is connected to the heat and momentum transfer at the interface. Even geometric changes affect the relative importance that the interface plays. This problem is also an important prototype of liquid encapsulated crystal growth and this is explained in the proposal. The PI expects that this study will answer some important questions on convective instability as related to multi-layer interaction, geometric variables, properties and heating direction. Such issues include the role of gravitational effects and a possible counter mechanism between buoyancy and interfacial tension gradient induced convection. The interesting aspect of generation of oscillations and the enhancement of heat transfer in this region will affect application to the problem of encapsulated crystal growth.