摘要:

Numerical results are presented of the simulation of combined buoyant and thermocapillary convection in a square cavity, and comparison is made with experimental observations of Schwabe and Metzger [1]. The two-dimensional conservation equations for mass, momentum, and thermal energy (temperature) are solved using a multigrid finite-volume method and grids with up to 248 X 200 control volumes. Central differencing is used to discretize both convection and diffusion fluxes, and the coupling of pressure and velocity is achieved via the SIMPLE algorithm for colocated variable arrangement [2]. The discretization accuracy of the results is estimated to be of the order of 1% on the finest grid. The agreement with experimental results is fairly good; the reasons for observed discrepancies are also discussed.

ISSN:1040-7782    

DOI:10.1080/10407789108944869

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The present investigation involves the prediction of film cooling from two rows of holes using different turbulence models. Predictions of film cooling effectiveness and the velocity field from two rows of holes inclined in the streamwise direction are presented using the k-ω model and a modified version of it, as well as the standard k-ϵ model together with its nonisotropic version. Comparison between the predicted results using these models and previous experimental results indicates that the ability of a turbulence model to prediet the experimental results depends heavily on the blowing rate as well as on the distance downstream from the injection holes.

ISSN:1040-7782    

DOI:10.1080/10407789108944870

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The transient behavior of the flow and temperature fields in a thick-walled pipe was analyzed by simultaneously solving for conduction in the pipe wall and for convection in the fluid stream. Two different transient situations were considered: the transient heat transfer in steady, developing pipe flow, and the simultaneous transient development of flow and heating in a pipe. In each case, a parametric study was done to understand the effects of ratio of watt thickness to inner diameter, Piclet number, ratio of wall to fluid thermal conductivities, and ratio of watt to fluid thermal diffusivities. All these parameters were found to significantly influence the duration of the transient as well as the distributions of Nusselt number, interfacial temperature, bulk temperature, and interfacial heat flux during the transient processes.

ISSN:1040-7782    

DOI:10.1080/10407789108944871

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A detailed numerical analysis has been carried out to study transient natural convection in a binary mixture adjacent to a vertical plate of finite height with the simultaneous presence of temperature and concentration gradients. The full elliptic Navier-Stokes equations and the energy and species diffusion equations were solved together by the projection method with the convective terms treated by the QUICK scheme. Computations were performed for a mixture with Pr = 0.7, Sc = 3.5, and thermal Grashof number fixed at 106. Both the augmenting and opposing flows were investigated with the buoyancy ratio varied from -5 to 5 and the concentration ratio, an interface velocity parameter, from 10 to 1000. Results are presented to illustrate, in particular, the effects of combined thermal and solutal buoyancy forces on the temporal evolution of the flow pattern and the associated heat and mass transfer. Representative transient velocity, temperature, and concentration profiles are presented, along with the transient local and average Nusselt and Sherwood numbers. In the initial transient, the interface velocity at the plate induced by the concentration gradient dominates the flow patterns. After the initial period, the recirculating flows generated by the two buoyancy forces in the fluid are prevalent. In opposing flows, countercurrent flows may result at a high buoyancy ratio.

ISSN:1040-7782    

DOI:10.1080/10407789108944872

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A high-resolution, finite-difference numerical study is reported on natural convection in a square cavity. The vertical sidewatts of the cavity are differentially heated, and a uniform internal heat generation is also present. Two principal parameters are considered, the internal Rayleigh number RaI, which represents the strength of the internal heat generation, and the external Rayleigh number Rag, which denotes the effect due to the differential heating of the side walls. The internal Rayleigh number varies in the range 1010RaI≤ 107, while the external Rayleigh number is set at RaE= 5 x 107for most computations. As the relative strength of the internal heat generation increases, the flows near the tap portion of the heated sidewall are directed downward. When the effect of the internal heat generation is dominant, the thermal energy leaves the system for the surroundings over the top portion of the heated wall. Only in the bottom pari of the heated wall is heat transfer directed into the system. These numerical solutions are in qualitative agreement with the available experimental measurements.

ISSN:1040-7782    

DOI:10.1080/10407789108944873

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Laminar natural convection in rectangular enclosures divided by a single thin partition is studied numerically by the finite-element method. Special emphasis is given to enclosures with aspect ratios less than 1, although the results for aspect ratios of 1 have also been reported for comparison. The effect on flow structure and heat transfer of shifting the partition in the enclosure has also been investigated. While the Prandtl number is held at unity, the Rayteigh number is considered over a wide range, that is, from 103to 106, and the aspect ratio assumed the values of I, 0.8, 0.5, and 0.4.

ISSN:1040-7782    

DOI:10.1080/10407789108944874

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor