摘要:

A survey article is presented which discusses the architecture of vector and parallel machines, the charcteristics of the machines that are currently available, and the computational gain that can be achieved using these new types of machine architectures. In addition, the literature and activities in the area of parallel computations in heat transfer and fluid flows are noted. To illustrate the high computing speeds that can be obtained on supercomputers, two heat transfer problems are solved on both scalar and vector machines. It is shown that the vectorized code executes two orders of magnitude faster on a supercomputer than the nonvectorized version on a standard, sequential mainframe computer.

ISSN:0149-5720    

DOI:10.1080/10407788608913499

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The solution of transient diffusion in a composite material consisting of several different materials involves solving the Sturm-Liouville problem with discontinuous coefficients. An efficient numerical method and algorithm are presented in this paper for finding eigenvalues, eigenfunctions, and the related coefficients. The method is straightforward and powerful. It can be applied to solve transient diffusion problems in various geometries with any number of layers of different materials. This is a considerable advantage over the commonly used Laplace transform method, which becomes tedious when applied to composite materials consisting of more than two layers of different materials.

ISSN:0149-5720    

DOI:10.1080/10407788608913500

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Laminar forced convective heat transfer in a two-dimensional 90° bifurcation is studied numerically. The governing elliptic equations are solved by a finite-difference numerical scheme utilizing primitive dependent variables. A wide range of Reynolds numbers and dividing flow rates is studied with air at constant properties as the working fluid, which is heated by the constant-temperature walls of the bifurcation. The locations of the separation and reattachment points corresponding to the two recirculatian zones that form in the bifurcation are quantified as a function of the Reynolds number and dividing flow rate. For a given dividing flaw rate, the sizes of the two recirculation zones increase as the inlet Reynolds number is increased. On the other hand, for a given Reynolds number, the sizes of the two recirculation zones increase as the dividing flow rate increases, but they reach maxima after which a higher dividing flow rate results in smaller recirculation zones. The variation of the local Nusselt number along the walls of the bifurcation is discussed in light of the direct effects of the highly perturbed flow field. The prevalence and extent of the false diffusion for this geometry are also examined. Excessive false diffusion is observed in regions where the velocity vector is not aligned with the computational grid.

ISSN:0149-5720    

DOI:10.1080/10407788608913501

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The characteristics of vortex instability for laminar free-convection flow over horizontal and inclined flat plates with prescribed uniform surface heat flux are studied analytically by the linear theory. The system of linearized disturbance equations constitutes an eigenvalue problem, which is solved numerically by a Runge-Kutta integration scheme along with a shooting technique. Neutral stability curves and critical Grashof numbers are presented for Prandtl numbers of 0.7 and 7 over a wide range of inclination angles, from the horizontal to close to the vertical orientation. The flow becomes more stable to the vortex mode of instability as the angle of inclination from the horizontal increases. It reaches an absolutely stable condition with respect to the vortex instability when the plate is vertical. In addition, fluids with a Prandtl number of 7 are more susceptible to instability than fluids with a Prandtl number of 0.7. The present results are also compared with available vortex instability results under the uniform wall temperature condition on the basis of equivalent Grashof and wave numbers.

ISSN:0149-5720    

DOI:10.1080/10407788608913502

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The unsteady buoyancy-induced flow generated by an isothermal flat vertical surface enclosed in a long rectangular cavity is numerically analyzed. The enclosed fluid is assumed to be Newtonian and the walls are adiabatic. The transient process is initiated by suddenly and uniformly raising the temperature of the surface to a steady value higher than that of the fluid in the cavity. The full two-dimensional conservation equations, representing mass, momentum, and energy balance, are solved using a modified finite-difference scheme originally called the simple arbitrary La-grangian-Eulerian (SALE) technique. The resulting transport is found to be composed of several distinct regimes. At very short times a quasi-one-dimensional conduction regime occurs adjacent to the surface. The temperature distribution and heat transfer coefficient are found to closely follow the known one-dimensional conduction solution. At intermediate times the flow adjacent to the surface is observed to resemble the boundary-layer regime near a semi-infinite surface immersed in an infinite medium. Finally, at later times the adiabatic boundaries cause the decay of the temperature gradients. Eventually, the velocity field decays through viscous dissipation effects.

ISSN:0149-5720    

DOI:10.1080/10407788608913503

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The problem of transient conduction from a heated cylinder to its surroundings is reviewed, and methods for calculating the transient temperature field are summarized. Three spatially uniform heat sources in the cylinder are studied: the impulse, step, and ramp sources. Both transform and finite-difference methods are examined, and results obtained with these methods are presented for a wide range of conductivities appropriate for most gases and liquids surrounding a conductive cylinder of varying length-to-diameter ratio.

ISSN:0149-5720    

DOI:10.1080/10407788608913504

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor