Numerical and experimental studies of heat transfer in steady and unsteady laminar or turbulent natural and mixed convective flows

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Research in five areas involving convective heat transfer will be undertaken. A number of electronic and electrical components are air-cooled using natural convection and involve geometric shapes that have not been dealt with in basic natural convective heat transfer studies. In the first part of the present work equations that can be used to predict the heat transfer rate in such situations will be developed. Both numerical and experimental studies will be undertaken. In the practical applications considered in the first area of research there is sometimes a low velocity flow over the components. The forced air velocity in such situations is often so low that the heat transfer is by mixed natural and forced convection. Such flows will be considered in the second area of research. Both numerical and experimental work will again be undertaken. The main aims of this work will be to define the conditions under which mixed convection exists. No systematic studies of numerical results obtained using a range of turbulence models for situations involving natural and mixed turbulent convective flows which are similar to air flows in buildings and for which experimental results exist have been undertaken. Such a study will be undertaken in the third study area, the main purpose being to derive recommendations as to which turbulence model to use in a particular flow situation. Most studies of heat transfer across window-blind systems assume that the natural convective flow over the room side of such systems is laminar. Turbulence and unsteady flow can, however, develop in such flows. Therefore in the fourth part of the research basic experimental and numerical studies of the development of turbulent and unsteady flow in window-blind systems will be undertaken. Gas flows in mini-channel systems in which the channel follows a wavy path will be considered in fifth part of the work. Such mini-channel systems are used in a number of practical situations and the flow in these systems can become unsteady at Reynolds numbers that are lower that that at which turbulent flow develops. The purpose of the study is to determine how the channel geometry affects the conditions under which unsteady flow develops.