摘要:

Two finite-difference methods are proposed for solving wave instability problems with and without coupling between momentum and energy equations. Neutral critical stability results are compared with those generated by the Runge-Kutta integration method in conjunction with an orthonormalization procedure. The new finite-difference methods are found to be very accurate, timesaving, and easy to program. They can also be applied to solve systems of high-order ordinary differential equations.

ISSN:0149-5720    

DOI:10.1080/10407788608913505

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Natural convection fluid flow and heat transfer has been studied numerically in the enclosed space between two concentrically positioned vertical cylinders having different finite heights. The cylinders were maintained at different uniform temperatures. The enclosed space was occupied by a system of two fluids, one situated atop the other in a layered manner. For the numerical work, consideration was given to three two-fluid systems: air-water, air-hexadecane, and hexadecane-water. Parametric variations were made of the position of the fluid-fluid interface and of the Rayleigh number. Another parameter was the retention or omission of the interfacial (surface) tension in the force balance at the fluid-fluid interface. The presentation of results included the patterns of fluid flow, velocity profiles, average Nusselt numbers, per-fluid heat transfer rates, and local heat flux distributions. Average Nusselt number definitions were constructed which virtually eliminated the dependence of the results on the location of the interface. Only the liquid-liquid system (hexadecane-water) was found to be sensitive to the interfacial tension.

ISSN:0149-5720    

DOI:10.1080/10407788608913506

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The flow in a twisted circular-sector duct is solved numerically for a steady, incompressible, hydrodynamically and thermally fully developed laminar flow. The wall of the duct is subjected to uniform heat flux per unit axial length with peripherally uniform temperature. A rotating cylindrical coordinate system is introduced to simplify the governing equations to two independent variables. The stream function and vorticity are adopted instead of the primitive variables of velocity and pressure. Friction factor and Nusselt number are presented for values of the duct angle from 11.25 to 90°, dimensionless twist ratio up to 0.7, and Prandtl number from 1 to 100. The results show that the influence of twist on friction and heat transfer is significant at high Reynolds numbers and high Prandtl numbers.

ISSN:0149-5720    

DOI:10.1080/10407788608913507

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The thermal feasibility of a newly proposed thin strip continuous casting process was investigated by using an extended finite-element model. The investigation is presented as a case study of how such a process can be modeled. Details of the thermal model are given, including the boundary-layer phase change technique developed for modeling the solidification process. Bonding of solidified melt to clad was investigated on a near-microscopic scale, using microsecond time steps to track the thermal shock of initial molten metal/clad contact. This casting process would provide a product with two quality surfaces at substantial energy savings over conventional full-thickness cast/rolled sheet production by using thin cold-rolled feedstock as a cladding. The candidate material used for study was ANSI-1020 carbon steel. Modeling parameter variations identified the melt-to-solid(clad) ratio of the product as the most important modeling and process parameter, with thermal feasibility demonstrated for values of this ratio ≤ 3.4.

ISSN:0149-5720    

DOI:10.1080/10407788608913508

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Numerical solutions of the simplified Navier-Slokes and continuity equations applicable to the laminar vapor flow in slender cylindrical heal pipes are presented. The number of unknowns is reduced to two by eliminating the pressure gradient term. A numerical marching procedure is used to solve the governing nonlinear differential equation. The effect of fractional and momentum pressure drops on the static pressure is studied for values of the wall Reynolds number in the range 2 to −5.

ISSN:0149-5720    

DOI:10.1080/10407788608913509

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The transient temperature distribution in a multilayer composite, semitransparent or transparent, absorbing and emitting medium that is suddenly exposed to a thermal radiative flux is investigated. Effects of both thermal radiation and conduction within each layer and convection on both exterior surfaces of the composite wall are considered. The internal heal generation from an electrically conductive thin-film heater is also considered. An analytic relation for obtaining the radiative flux in the multilayer stack is presented. Transient temperature solutions are obtained by a hybrid numerical algorithm. Illustrative solutions are presented for the transient surface temperature of a multilayer transparent medium after exposure to a very high radiative flux. Various surface reflectivities are examined.

ISSN:0149-5720    

DOI:10.1080/10407788608913510

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor