摘要:

A skewed upwinding procedure is presented for application to the control-volume-based finite-element computation of convective-diffusive transport problems. The method is based on the application of sound physical arguments and further introduces a novel procedure for consideration of convecting flows that vary strongly in both magnitude and direction. Through its basis of development, the procedure inherently precludes the possibility of developing nonphysical spatial oscillations within the solution domain. The procedure is demonstrated by application to two test problems for which its performance has proven to be excellent. The method possesses relatively low levels of false diffusion, is relatively insensitive to grid orientation, demonstrates symmetric characteristics about the centerline of a step-change convective transport, and produces solutions completely free from undesirable spatial oscillations. This latter attribute, in conjunction with its very modest false diffusion levels, renders the procedure attractive for a broad spectrum of problems.

ISSN:0149-5720    

DOI:10.1080/10407788608913462

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A new space-marching finite-difference algorithm is developed to solve the nonlinear inverse heat conduction problem. This algorithm uses interior temperature measurements at future times to estimate the surface heat flux. The results of this method are compared on a test case with four other numerical schemes. The method is as accurate as the method developed by Beck [ 1] and uses a smaller computational time. This scheme is also employed to estimate the effects of different types of experimental errors on the estimation of the surface heat flux. Errors due to temperature measurements, thermocouple locations, and material properties are each investigated.

ISSN:0149-5720    

DOI:10.1080/10407788608913463

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The nodal domain integration method is applied to a radially symmetric heat conduction problem where the solution domain is discretized into irregular radial finite elements, and the state variable is approximated by a spatial linear trial function within each finite element. The resulting finite-element model represents the well-known Galerkin finite-element, subdomain-integration, and an integrated finite-difference numerical statement as well as an infinity of other mass-lumped matrix schemes. From the NDI approach, the several numerical modeling techniques are unified into one global domain model where each submodel can be obtained by the specification of a single mass-lumping parameter.

ISSN:0149-5720    

DOI:10.1080/10407788608913464

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

A methodology is set forth for the numerical solution of transient two-dimensional freezing of a phase change medium contained within a closed vertical tube. The transient is initiated when the containment tube, which is initially filled with a liquid whose temperature is above the fusion value, is exposed to an external fluid environment having a below-fusion temperature. The solution domain encompasses the liquid and solid phases and the tube wall. Natural convection occurs in the liquid phase. Coordinate transformations are employed to immobilize and to straighten the moving, curved interface which separates the solid and liquid phases. The finite-difference equations for the temperature and velocity fields are derived using a con-trot volume approach and an implicit treatment of the time wise variations. The energy balance at the solid-liquid interface is discretized explicitly to provide a means for determining the movement of the interface as freezing proceeds. Numerical results obtained by applying the methodology are presented in a companion paper which follows.

ISSN:0149-5720    

DOI:10.1080/10407788608913465

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Numerical solutions for freezing of a phase change medium contained in a sealed vertical tube were carried out using the methodology developed in the preceding paper in this issue of the journal. The solutions took account of natural convection in the unfrozen liquid and heat conduction in the tube wall, as well as heat conduction in the frozen layer. For the investigated problems, the freezing was initiated when the external surface of the tube was exposed to a fluid environment whose temperature was lower than the phase change temperature. The numerical solutions provided information on the response of the freezing process to changes in the tube wall thickness and tube wall material and to changes in the convective heat transfer coefficient at the external surface of the tube. For each case, time-dependent results were obtained for the amount of frozen mass, the profile of the solid-liquid interface, and the temperature distributions at the inner and outer surfaces of the tube. Comparisons were made between the numerical predictions and experimental data, and good agreement was found to prevail.

ISSN:0149-5720    

DOI:10.1080/10407788608913466

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The flow in the region between two infinite rows of rectangular compacts lying between two planes is considered in an attempt to model the heat transfer and fluid flow near the bounding wall of a packed bed. In this region it is known that the voids are larger than those in the center of the bed, giving rise to an enhanced flow near the wall. The equations governing the fluid flow and heat transfer are solved numerically for a range of compact-plane separations and compact-compact separations, with Prandtl numbers of 0.72 and 7.0 and Reynolds numbers ranging from 0 to 50. It was found that as the Reynolds number increased, the heat transfer from the void decreased, although increasing the void size led to some improvement in the heat transfer from the void. Also, the heat transfer from the void increased when the Prandtl number decreased, but when the compact-plane separation was increased the heat transfer in the void was greatly reduced with the temperature of the fluid becoming nearly uniform.

ISSN:0149-5720    

DOI:10.1080/10407788608913467

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0149-5720    

DOI:10.1080/10407788608913468

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor