摘要:

A finite-element method for predicting flow through ducts of arbitrary and varying cross sections is presented. The governing differential equations are discretized using a control-volume approach. For this purpose, specially constructed three-dimensional control volumes are employed. The method is of the marching type and is based an a fully implicit formulation. Here, in part I of the paper, only the basic methodology is described; in the accompanying pan II, results of application of the method to some test problems are presented.

ISSN:0149-5720    

DOI:10.1080/10407788708913594

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

In part I of the paper, a control-volume finite-element method for predicting flow and heat transfer through ducts of arbitrary cross sections was described. This paper, part II in the two-part sequence, discusses application of the proposed method to some test problems. Our main interest is in predicting flow through ducts of varying cross sections. However, unfortunately, for ducts of varying cross sections, nothing is available in literature that can be used as a benchmark. This recognition necessitated the adoption of an alternative approach. In this paper, a procedure is described for formulating problems involving flow through ducts of arbitrary cross sections for which the exact solution is known. Such problems, with known exact solutions, then serve as benchmarks to validate the numerical method. Cases considered include a square diffuser and a deforming elliptic duct.

ISSN:0149-5720    

DOI:10.1080/10407788708913595

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This paper describes the numerical study of the phenomenon of natural convection in an enclosure fitted with a partial vertical adiabatic partition. The partitions are parallel to the two vertical isothermal enclosure walls, which are maintained at different temperatures while the horizontal walls of the enclosure are adiabatic. The governing equations are solved with the aid of a cubic spline collocation method. Parametric studies of the effects of the partial vertical divisions on the fluid flow and temperature fields have been performed and results are presented and discussed. The heat transfer rate across the partitioned enclosure is also studied.

ISSN:0149-5720    

DOI:10.1080/10407788708913596

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The finite-difference solution for the temperature distribution within a sphere exposed to a nonuniform surface heat flux involves special difficulties because of the presence of mathematical singularities. For this reason, the adequacy of some finite-difference representations of the heat diffusion equation is examined. In particular, neglecting the contribution from the term causing the singularity is shown as an accurate and efficient method of treating a singularity in spherical coordinates. A method based on the superposition principle is investigated and found quite suitable for this kind of problem in spherical coordinates.

ISSN:0149-5720    

DOI:10.1080/10407788708913597

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Finite-volume computations are reported for the fully developed turbulent flow through a square-sectioned duct rotating about an axis perpendicular to that of the duct at a Reynolds number of 5 × 104. Two turbulence models are used to represent the turbulent stresses and heat fluxes in the main part of the flow: the standard k-ε eddy-viscosity model (EVM) and an algebraic second-moment closure(ASM). In the semiviscous sublayer adjacent to the wall a generalization of Van Driest's version of the mixing-length hypothesis is adopted. Quadratic upstream discretization of momentum and energy convection is used with grid densities up to 65 × 127.

ISSN:0149-5720    

DOI:10.1080/10407788708913598

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This investigation is about laminar natural convection through an open-ended vertical annulus with a rotating inner cylinder, one uniformly heated boundary, and one adiabatic boundary. The boundary-layer equations governing this case have been solved by means of a finite-difference scheme and results are presented for a fluid of Pr = 0.7 in an annulus of radius ratio 0.5. These results clarify the characteristics of the induced flow due to a constant heat flux at one of the boundaries. The development of the tangential boundary-layer displacement thickness is also given, so that Astill's criterion for hydrodynamic instability can be utilized.

ISSN:0149-5720    

DOI:10.1080/10407788708913599

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Numerical solutions are found for the similarity formulation of the equations, closed with an eddy viscosity model, governing the flow in a buoyant plume in a stratified environment. The effects of the stratification on the velocity and temperature profiles are studied. Comparisons between computed results and experimental data are made.

ISSN:0149-5720    

DOI:10.1080/10407788708913600

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor