摘要:

A numerical method for the solution of two-phase flow equations has been developed. The method is based on the commonly used principles for the solution of two-phase flow: a staggered mesh, an upwind treatment of the convection terms, and the implicitness of the transfer terms. The purpose was to develop a robust and fast method for the analysis of nuclear reactors. Consequently, the equations are solved in a one-dimensional form, but the principles of the method are also applicable for multidimensional solutions.

ISSN:0149-5720    

DOI:10.1080/10407788708913571

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

An IBM PC was used to obtain finite-difference solutions to a complex heat transfer and fluid flow problem in which the solution domain contained nearly 6000 grid points. The investigated problem was the abrupt, asymmetric enlargement of a parallel-plate channel. The enlargement lakes the form of a backward-facing step, the presence of which causes separation of the flow. Heat transfer occurred at the channel wall which extended downstream from the foot of the step. The present velocity solutions were shown to be at least as accurate as prior numerical solutions and served to extend the range of investigated enlargements. The variation of the local Nusselt number with the Reynolds number took on different forms at various axial distances from the enlargement step. In a region extending downstream from the step, the Nusselt number actually decreased monotonically with increasing Reynolds number. Farther downstream, the Nusselt-Reynolds variation was monotonically increasing, while still farther downstream, the Nusselt number was independent of the Reynolds number.

ISSN:0149-5720    

DOI:10.1080/10407788708913572

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The process of freeze coating of a polymeric melt on an axially moving continuous cylinder is studied numerically by a finite-difference method, taking into account heat convection from the melt to the freeze coat and spatial variation of the cylinder temperature. The solid-liquid interface location is immobilized in the finite-difference analysis of the problem by transforming the system of equations governing the behavior of the freeze coat and the cylinder temperature into a dimensionless space. Various controlling parameters of the system are identified and their effects on the growth-and-decay behavior of the freeze coat are determined. Also determined are the maximum freeze-coat thickness and the corresponding axial location, based on which criteria for selection of the optimum freeze-coating operation conditions are established. The accuracy of the computational scheme is demonstrated by comparing the numerical results with the similarity solutions that are valid at small dimensionless axial locations.

ISSN:0149-5720    

DOI:10.1080/10407788708913573

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The equations governing laminar flow past a sphere with surface mass transfer were solved numerically for low to moderate Reynolds numbers. The Reynolds number range considered was between 1 and 130. For mass transfer the Schmidt number was set equal to 1. Results of the calculations presented here include wake lengths, angles of separation, drag coefficients, and average Sherwood numbers. These predictions compare well with published experimental observations and other numerical results.

ISSN:0149-5720    

DOI:10.1080/10407788708913574

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

This paper reports the main results of a series of numerical experiments documenting the phenomenon of convective instability in a horizontal heat-generating porous bed underlying a fluid layer. The problem of interest was modeled with the help of a general flow model for the porous bed. This model accounts for the effects of flow inertia and macroscopic shear in the porous substrate. Both these phenomena are neglected in the more popular Darcy flow model for porous media. The numerical experiments focus primarily on the parametric domain in which the flow in the system is well established, that is, the value of the Rayleigh number is larger than critical. The dependence of the maximum temperature inside the heat-generating porous matrix on the representative dimensionless groups of the problem is predicted. The effect of these groups on the flow field (number, intensity, and shape of convection rolls) and on the temperature field is determined and illustrated for a number of characteristic cases.

ISSN:0149-5720    

DOI:10.1080/10407788708913575

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Natural convective steady-state motion inside a bidimensional semielliptic cavity is investigated numerically by means of a finite-element algorithm. The ceiling of the cavity is kept at a known temperature with a sinusoidal spatial distribution and the floor is assumed thermally insulated. A parametric study is carried out by varying the aspect ratio and the Grashof number. The convective motion is found to be composed of a main cell plus two small corner cells, one of which disappears at high Grashof numbers or aspect ratios. Heat is transferred mainly across the upper part of the cavity, the lower portion remaining essentially isothermal.

ISSN:0149-5720    

DOI:10.1080/10407788708913576

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Steady laminar natural convection flow in a cylindrical enclosure with an aspect ratio (height to radius) of unity has been analyzed numerically for 102≤ Ra ≤2 × 105. The enclosure consists a cold bottom wait and hot side and top walls. Physical geometry and boundary conditions were made to simulate the presence of oil storage tanks in the petroleum industry and passive solar heating for energy-efficient buildings. The flow field is found to consist of two large recirculating zones, both of which are symmetrical. Results indicate that a major fraction of the total heat transfer comes from the bottom wall. The Prandtl number effect is also presented for 1 ≤ Pr ≤ 200.

ISSN:0149-5720    

DOI:10.1080/10407788708913577

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor