Showing papers by "Yutaka Asako published in 1987"

Finite-volume solutions for laminar flow and heat transfer in a corrugated duct

Abstract: A finite volume methodology was developed to predict fully developed heat transfer coefficients, friction factors, and streamlines for flow in a corrugated duct. The basis of the method is an algebraic coordinate transformation which maps the complex fluid domain onto a rectangle. The method can be adopted for other convection-diffusion problems in which two boundaries of the flow domain do not lie along the coordinate lines. Representative results were found for laminar flow uniform wall temperature, and for a range of Reynolds number, Prandtl number, corrugation angle, and dimensionless interwall spacing. As seen from the streamlines, the flow patterns are highly complex including large recirculation zones. The pressure drops and friction factor results are higher than the corresponding values for a straight duct. Finally, the performance of the corrugated duct was compared with the straight duct under three different constraints - fixed pumping power, fixed pressure drop, and fixed mass flow rate. There are small differences in the heat transfer rate ratios under these constraints.

Numerical determination of heat transfer and pressure drop characteristics for a converging−diverging flow channel

Abstract: A finite difference scheme was utilized to predict periodic fully developed heat transfer and fluid flow characteristics in a converging-diverging flow channel. The basis of the method is an algebraic nonorthogonal coordinate transformation which maps the complex fluid domain onto a rectangle. This transformation avoids the task of numerically generating boundary-fitted coordinates. The transformed equations and the entire discretization procedure were documented in an earlier paper which dealt with a general class of nonperiodic problems. Its adaptation to a periodic sample problem of converging-diverging flow channel will be illustrated in this work. Representative results were carried out for laminar flow, Prandtl number of 0.7, in the Reynolds number range from 90 to 1,635, for various taper angles of converging-diverging flow channel, and for three ratios of maximum/minimum height of the flow channel. Moderate enhancement in the Nusselt number results occurred, at higher values of Reynolds number for most cases, when compared with corresponding values for straight ducts.

Natural Convection Heat Transfer in a Vertical Air Slot Partitioned by Corrugated Plates

Abstract: Natural convection and heat transfer in a vertical air slot partitioned by corrugated plates have been analyzed by the finite-element method to investigate the heat transfer characteristics as an insulating wall. The modified Galerkin method was used for the formulation. The computations were performed for the Prandtl number 0.7 in the Rayleigh number range from 103 to 106. Two thermal boundary conditions were considered for the partition plate: the conduction case and the no-thickness case. In the case of no thickness, radiation heat flux was included in the heat balance on the partition plate. The radiation effect was examined for a wide range of emissivities. The heat transfer performance was compared with that for the flat partition plate case. Both convection and radiation heat transfer rates for the corrugated partition plate are less than those for the flat partition plate.

Heat transfer and pressure drop characteristics in a converging-diverging duct with rounded corners.

Abstract: Calcul numerique pour un nombre de Prandtl de 0,7 et des nombres de Reynolds de 100 a 1000 pour differents angles de la conduite conique. Les coins arrondis diminuent le frottement