Errors of numerical solutions for unsteady heat conduction problems by two different methods were evalued, compareing with analytical solutions, two methods were implicit and Crank-Nicolson method. Differences of numerical solutions and analytical solutions were very small and increased with dimensions of problems in three dimensional problems, errors of numerial solution by Crank-Nicolson method were about 0.7% in central portion of analytical region.

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Usually many convergent nozzles are used in a flow condition of correct expansion. But, in this paper the flow condition of under-expansion is very complicated in comparison with correct expansion. These multi convergent nozzles with under-expansion were used for heat transfer enhancement from the heating surface to the air jet. As a result, the local heat transfer coefficients were influenced by Reynolds number and the distance between these nozzles and the heating surface.

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The heat transfer enhancement using the parallel wires above the heating surface was investigated. The convergent nozzle was used, its diameter was 3.0mm, and the diameters of the fine wire used in this study were 0.8mm. 1.0mm, 1.2mm, and these pitches of the wires were 2.0mm, 2.5mm. 3.0mm. As a result, the heat transfer coefficient was increased by using the parallel wires above the heating surface in comparison without the wire.

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Electro-Rheological fluid (ER fluid) is a kind of functional materials. The ER fluid changes its apparent viscosity (a rheological characteristics) when an electric field is applied to it. Many types of ER fluids have developed these days. In this study, we discuss development of a variable damper using macromolecular liquid crystalline ER fluid.

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