摘要:

A calculation procedure is described for calculating flows that are partially elliptic and three-dimensional in nature. A partially elliptic flow is one that features a recirculating zone that is embedded within a partially parabolic mainstream. This calculation procedure, with but slight modifications, is economical of computer storage since it is only in those areas where flow reversal is encountered that three-dimensional storage of variables is necessary. To illustrate the results, the laminar flow in a tee-junction is presented; the predictions are obtained by using a partially elliptic procedure and a fully elliptic procedure. Good agreement is obtained when the results of the procedures are compared.

ISSN:0149-5720    

DOI:10.1080/10407787908913412

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Effects of curvature on the fluid flow and heat transfer with axially uniform wall heat flux and peripherally uniform wall temperature in a tube are analyzed numerically. Solutions are available over a wide range of Prandtl numbers and Dean numbers up to 1305. It is found that the secondary flow circulations become more complex as the Dean number increases. Nusselt number increases are most evident at high Prandtl and Dean numbers. The introduction of a convergence parameter into the alternating direction implicit solution method results in substantially reduced computation time. A method of finding the optimum convergence parameter is described.

ISSN:0149-5720    

DOI:10.1080/10407787908913413

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

This paper presents a generally applicable approach to a step-by-step analysis of developing laminar flow in straight ducts of arbitrary but constant shape. A three-level central algorithm that does not require iterations is used to march ahead with the solution in the axial direction. The calculation procedure is implemented by utilizing, with minor modifications, a standard finite-element code for nonlinear heat conduction. Several illustrative examples demonstrate the accuracy and versatility of the proposed technique.

ISSN:0149-5720    

DOI:10.1080/10407787908913414

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Linear stability analysis for study of the connective instability of a horizontal liquid layer in a porous medium subjected to a temperature gradient is approached by both finite-difference and finite-element methods for the case with uniform vertical throughflow and maximum density effects. Numerical results for the critical Rayleigh number are presented for the thermal condition parameters − 3.5 < λ1 < − 0.5 and − 1.4 < λ2 < 1.4 with Peclet number Pe = 0, 0.5, 1, 5, and 10. The convergence and accuracy of the numerical solutions are assured by the excellent agreement of the critical Rayleigh numbers for the limiting cases with the known values.

ISSN:0149-5720    

DOI:10.1080/10407787908913415

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

A significant reduction in computing time and memory requirements has been obtained for the numerical computation of nonequilibrium condensation in one-and two-dimensional supersonic two-phase flow. The accuracy and especially the stability of both the Kentzer-Moretti scheme and a predictor-corrector scheme based on the method of characteristics have been critically evaluated by numerical calculation of flow quantities at the domain boundaries for this hyperbolic case. Both schemes have proved to be stable.

ISSN:0149-5720    

DOI:10.1080/10407787908913416

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

A numerical analysis is carried out about the thick boundary layer of steady laminar free convection around a horizontal circular cylinder by a finite-difference method. The results for the average heat transfer coefficient for Pr = .0.7, 10, and 100 and 10−4 < Gr  <  104are expressed within an accuracy of 1% as follows:whereand C(Pr) is a function of Pr. This expression agrees well with experimental data in the range 10−10 < Ra  < 107. Also discussed are the principal terms in the equations for the thick boundary layer, the technique of numerical calculation, the radial distribution of velocity components and temperature, and the azimuthal distribution of iocal Nusselt number, and the results are compared with previous theoretical results for the average Nusselt number.

ISSN:0149-5720    

DOI:10.1080/10407787908913417

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Consideration is given to laminar flow in a channel from which a blocked branch line emanates at right angles. The channel and the branch line constitute a solution domain that is nonregular with respect to computer codes structured to deal with domains that are rectangular. As an application of a technique devised by Patankar, the nonregular domain was transformed into a rectangular domain within which the fluid experiences a stepwise change of viscosity, taking on infinite viscosity in regions where flow is not to exist. Numerical solutions were obtained for parametric values of the channel Reynolds number and of the dimensionless length of the blocked branch line. The results showed that the greatest disturbance of the main flow by the presence of the branch line occurs at low Reynolds numbers, but that the recirculation bubble in the branch line is more vigorous at high Reynolds numbers. The pressure drop in the channel is diminished by the presence of the branch line. The extent of the diminution is insensitive to the length of the branch line for lengths greater than a threshold value.

ISSN:0149-5720    

DOI:10.1080/10407787908913418

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

A numerical simulation is reported of the developing asymmetrically heated pipe flows measured by Black and Sparrow [1], particular attention being given to the anisotropy of the turbulent thermal diffusivities. The results suggest that the flows considered require approximately 150 diameters from the start of heating to reach full development (Nusselt numbers independent of streamwise position), nearly three times as for downstream as the position where the data of [1] were obtained. Provided one recognizes that the experiments do not correspond to the fully developed state, excellent agreement with the data is obtained by assuming the ratio of tangential:radial diffusivities to equal the ratio of the mean square velocity fluctuations in these directions.

ISSN:0149-5720    

DOI:10.1080/10407787908913419

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The TCLUSTI computer code has been developed to study the transient thermal performance of a liquid metal fast breeder reactor (LMFBR) subassembly that is thermally coupled to its six immediate neighbors. Each of the seven subassemblies may be either a reflector subassembly, which contains a single solid hexagonal rod. or a pin-bundle subassembly. The TCLUSTI analytical model, which is based on conservation of energy, and the numerical solution method, which employs successive over-relaxation (SOR) are described. Analytical temperature predictions are compared with data obtained from a natural-convective flow test performed in Experimental Breeder Reactor II. Good agreement is obtained between the analytical and measured results.

ISSN:0149-5720    

DOI:10.1080/10407787908913420

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Monte Carlo simulation is employed as a tool to investigate the sensitivity and uncertainty of a Stefan moving boundary problem. In the particular ice-water freezing problem employed, the physical property with the largest sensitivity is the ice thermal diffusivity. The ice buildup time for an initial thickness of 5 cm is 3·40 ± 0·19 h. representing a coefficient of variation of 5.6% as the total uncertainty.

ISSN:0149-5720    

DOI:10.1080/10407787908913421

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor