摘要:

Conjugate convection/conduction numerical simulations have been performed to determine flow and heat transfer phenomena associated with using a single laminar slot jet to cool a linear array of discrete heat sources. Flow is restricted to a channel formed by an impingement surface, within which the heat sources are flush mounted, and a parallel confinement surface, through which the jet is discharged. Calculations reveal a primary recirculation cell between the jet and the confining surface and, for restricted conditions, a secondary cell on the impingement surface that produces a maximum and a minimum in the distribution of the local convection coefficient. The effects of the jet velocity profile and pertinent dimensionless parameters on flow and heat transfer conditions have been calculated

ISSN:1040-7782    

DOI:10.1080/10407789208944762

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Fluid flow and thermal transport have been numerically investigated for a heated plate moving with and within a uniform forced flow. Two forced-flow circumstances involving a plate moving in a channel are considered in this study, one with uniform flow at the inlet and one in a uniform free stream in an extensive medium. These circumstances are of interest in a wide variety of manufacturing processes, such as continuous casting, extrusion, wire drawing, and fiber drawing. A detailed numerical study is carried out, assuming two-dimensional, laminar, transient flow. The governing full elliptic equations are solved by employing finite-difference and finite-volume methods. The transport in the solid material is coupled with that in the fluid through the boundary conditions, and simultaneous solutions for the two are obtained. The numerical simulation of such conjugate transport processes is discussed, and the considerations important to obtain accurate results for a wide variety of practical problems that involve a moving material subjected to heat transfer are outlined. Numerical results are obtained for the flow field and for the temperature distributions in both the solid and the flow. The numerical imposition of the boundary conditions is shown to be a very important aspect of the simulation. The two forced-flow circumstances considered have to be treated quite differently because of the nature of the resulting flow. The effect on the results is also determined for the relevant parameters that arise in the numerical scheme. The numerical results obtained indicate that the penetration of the conductive effects upstream of the point of emergence is significant. When a plate moves in a channel flow, the effect of channel width on the resulting heat transfer rate is significant, at least over ranges of practical interest. However, when the channel width increases, the resulting heat transfer in the case of a plate moving in a channel flow approaches the value obtained in the case of a plate moving in a free stream, as expected.

ISSN:1040-7782    

DOI:10.1080/10407789208944763

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Steady, three-dimensional natural convection in a rectangular parallelepiped filled with a saturated porous medium is analyzed numerically. Convergence of the current three-dimensional model is enhanced using a mutiigrid method. Three new cases are studied in addition to a known case (used to validate the solution) A new approach for calculating heat flow rate at walls is developed by applying the principle of an overall heat balance. The geometry encompasses different aspect ratios, while the boundary conditions combine the influence of the internal and external heat flows in terms ofBiot number. The current analysis shows that the heat flow rate is a strong function ofRayleigh number, the geometry, and the boundary conditions

ISSN:1040-7782    

DOI:10.1080/10407789208944764

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A control volume based procedure has been developed that makes possible the materially meaningful inclusion of radiation heat transfer in full simulation calculations for the axisymmetric version of the “ modified discretized-intensity method.” Included in this procedure is an innovative technique that splits the radiation problem in two. Bach subprob-lem, in turn, can be solved more effectively than if the problem had not been split, making the overall approach just as effective in optically thin absorbing-emitting media as it is in optically thick media. The mass absorption coefficients used in the formulation are based on a molecular band analysis and are computed at a finite number of discrete locations along each intensity ray. The model has applicability to any control volume energy balance formulation. A description of the incorporation of the model into a primitive variable approach is given. Application of the model is made to the solution of a portion of the combustion stroke of a four-stroke piston engine to demonstrate the utility of the model in moving boundary problems

ISSN:1040-7782    

DOI:10.1080/10407789208944765

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Numerical simulations are presented for transient and steady laminar buoyancy-driven flows and heat transfer in a square cavity open on one side. Computations were performed within the domain of the cavity. Vorticity transport and energy equations were solved using the alternating direction implicit scheme, and a successive overrelaxation method was employed to obtain solutions for the streamfunction. A range of values were considered for Gr and Pr. The results indicate that natural convection in the cavity does not depend on the computational domain or on the boundary conditions at the open side, which influence only a small region nearby. Heat transfer from the cavity is calculated, and flow and transport characteristics are discussed

ISSN:1040-7782    

DOI:10.1080/10407789208944766

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper describes the effects of element size and formula used for the calculation of temperature gradients on the local and average Nusselt numbers of natural convection for the widely used Galerlan finite-element method. Two cases of laminar two-dimensional natural convection are examined, namely, a fluid layer and a porous layer. The numerical error in the Nusselt numbers decreases with decreasing element size. The maximum error occurs at the position of a maximum of the local Nusselt number. In addition to the effect of element size, the Nusselt numbers are shown to vary with the formula used for calculating temperature gradients. The Nusselt numbers extrapolated to zero element size for different formulas are found, in both cases, to be virtually identical and also to agree well with the experimental data and the results computed by finite-difference methods

ISSN:1040-7782    

DOI:10.1080/10407789208944767

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor