摘要:

Hutchinson and Raithby [10] proposed a simple additive correction multigrid (ACM) method that has proved effective in reducing the cost of solving an algebraic equation set for a single variable. The equations of fluid motion and heat transfer lead to coupled sets of equations. The present paper outlines how ACM can be extended to solve these equations and reports results for a fluid dynamics and a natural convection problem (where the temperature-velocity coupling is important). The application of ACM to the coupled equations proves to be extremely attractive.

ISSN:0149-5720    

DOI:10.1080/10407788808913608

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The proper design of heat pump systems that use deep boreholes to extract heat from the ground requires a precise model of the thermal processes in the ground. One problem is the interaction between the connective heat flow in the channels in the borehole and the conductive process in the ground. Another important problem is the thermal interaction between boreholes. A computer model for these thermal processes is presented. The three-dimensional problem with its complex geometry is, by a rather intricate superposition, reduced to cylindrically symmetric ones, one for each borehole or symmetry group of boreholes. Recipes for the choice of meshes are given. The accuracy of the model is shown to be very good.

ISSN:0149-5720    

DOI:10.1080/10407788808913609

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

This paper considers transient conjugate heat transfer in the matrix of a thermal regenerator. Analysis is presented for the two-dimensional temperature fields in the fluid and solid for both laminar and turbulent flows. The independent governing parameters were identified and the equations were solved using finite-difference techniques. Results were obtained for a selected range of parameters. The range of parameters was identified wherein conjugate heat transfer and two-dimensional effects are significant. The results showed that the role of conjugate heat transfer is insignificant for flow through wide channels (γ ≥ 2)

ISSN:0149-5720    

DOI:10.1080/10407788808913610

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A Galerkin-type finite-element approach was used to study the effect of two-dimensional wall conduction on laminar convective heat transfer inside pipe flows. This conjugate heat transfer problem was studied for cases in which the external surface of the pipe is subjected to constant wall heat flux and constant wall temperature conditions. The wall conduction effects were found to be more significant for low Peclet number flows than their high Peclet number counterparts. The extent of preheating extends as far as 22 radii and 7 radii for constant wall heat flux and constant wall temperature conditions, respectively.

ISSN:0149-5720    

DOI:10.1080/10407788808913611

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Numerical predictions of the local Nusselt number for the curved three-dimensional incompressible turbulent flow of air with heat transfer in a square-sectioned duct with a 180° bend are presented and compared with experiment. The results are obtained using a finite-volume discretization of the Reynolds and energy equations employed in a semielliptic algorithm that marches repeatedly through the computational domain until convergence is reached. Results for each of three wall treatments that model the flow and heat trasnsfer in the thermally important near-wall region are compared. The first treatment uses Prandtl's mixing length hypothesis with van Driest's damping function in a fine near-wall grid approach. The other treatments are “two-layer” approaches in which near-wall effects are integrated for a relatively coarse near-wall mesh. The two two-layer models are constructed to allow diffusion of turbulent kinetic energy in near-wall regions and are therefore more general than “local-equilibrium” treatments. The dimensionless width of the viscous sublayer (VSL) is assumed to be constant for the first two-layer treatment but allowed to vary for the second. Core flow is simulated using the standardk − ε turbulence model. The objective of this study is to determine the viability of the turbulence model and wall treatments developed using two-dimensional flow data for the present flow in predicting the local Nusselt number at Reynolds numbers based on hydraulic diameter of 5.6 × 104and 9.2 × 104. Results for the two-layer approaches are broadly satisfactory, while the treatment assuming a constant dimensionless VSL width compares most favorably with the data. Broad agreement with experiment is achieved for local Nusselt number predictions even though significant disagreements occur between velocity field predictions in the core and the data. Discrepancies between predictions of the Nusselt number and experiment are at least partially attributed to the turbulence model, which fails to simulate near-wall anisotropy in the turbulence stresses.

ISSN:0149-5720    

DOI:10.1080/10407788808913612

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The steady-state combined conduction and radiation heat transfer for an absorbing, emitting, and isotropically scattering two-dimensional rectangular enclosure is investigated. The boundary surfaces art considered to be black and subjected to a constant temperature on one surface and to zero temperature on others. The Galerkin method is used to obtain an exact solution to the radiation part of the problem, and a finite-difference scheme is applied to solve the conduction part. The effects of the conduction-to-radiation parameter, the single scattering albedo, and the aspect ratio on the temperature distribution are examined.

ISSN:0149-5720    

DOI:10.1080/10407788808913613

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Pressure boundary conditions satisfying the normal momentum equation at solid boundaries with second-order accuracy are developed. Implementation of these conditions in an explicit numerical procedure for the two-dimensional incompressible Navier-Stokes equations enables convergent and accurate solutions for the driven cavity problem provided that the integral constraint of the Neumann boundary conditions is satisfied.

ISSN:0149-5720    

DOI:10.1080/10407788808910002

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The flow of metal subjected to a laser beam is analyzed. The model presented takes into account changes of the laser beam intensity in time and in cross section. This nonlinear phenomenon is solved using the finite-element method. Numerical examples complete the analysis presented.

ISSN:0149-5720    

DOI:10.1080/10407788808910003

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The numerical code and the results of calculations using a finite-element method for a two-dimensional laminar nonisothermal shear-driven flow in a square cavity are presented. The calculations were performed for the Reynolds number Re = 100 and Prandtl number Pr = 1 and for the exponent β = 1 to 2.2 in the viscosity formula μ = μ0 exp[−β(T − T0)]. The effect of the exponent β on the flow pattern and heat transfer from the moving lid to the bottom of a cavity is shown.

ISSN:0149-5720    

DOI:10.1080/10407788808910004

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0149-5720    

DOI:10.1080/10407788808910005

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor