摘要:

Steady laminar natural convection heal transfer in a two-dimensional, partially or fully open square cavity with three equally heated walls and various inclination angles is analyzed numerically. The overall average Nusselt number for a fully open cavity is approximately half the previously obtained average Nusselt number for a cavity with a heated back wall and insulated top and bottom walls for the same Rayleigh number. The dimensionless flow rale through the cavity is about twice the flow rate through the cavity with a healed back wall and two insulated walls. The effects of an aperture and cavity orientation, with respect to the direction of gravity, on natural convection heat transfer in the cavity are clarified.

ISSN:1040-7782    

DOI:10.1080/10407788908944696

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The phenomenon of natural convection caused by combined heat and mass transfer is studied numerically in a two-dimensional square cavity with insulated horizontal walls. The method is a combination of the Gauss-Seidel iterative technique and optimum under-relaxation. Results are obtained for steady-state flow with various: temperature and molar fraction boundary conditions for the vertical walls and various heat and mass Grashof number values, in the case when buoyancy forces due to simultaneous transfers are opposed.

ISSN:1040-7782    

DOI:10.1080/10407788908944697

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Forced convection heat and mass transfer, from a surface made of solid cylinders and its voids that are partially filled with a liquid, are studied numerically using a unit cell model. The predictions are compared with those available from boundary-layer treatment of partially liquid-covered planar surfaces. The results show that as the surface liquid saturation decreases and the Reynolds number increases, a vortex is formed in the partially filled voids. This vortex moves upstream as the Reynolds number increases, and its presence makes the mass transfer characeristics substantially different from those for planar surfaces. The results also show that in limited cases, the ratio of the total mass transfer rate to total heat transfer rate can be approximated by the fraction of the surface area covered by the liquid.

ISSN:1040-7782    

DOI:10.1080/10407788908944698

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A basic understanding of the highly nonlinear interaction effects of closely spaced spheres on fluid mechanics and heat transfer parameters is important for improving the design of a variety of thermal fluid-particle systems. Fluid flow patterns, isotherms, as well as Nusselt number distributions and extended correlations are presented for steady laminar axisym-metric flow past a linear array of three spheres. A finite-element method is used to solve the complete Navier-Stokes and heat transfer equations for the system parameter ranges 1⩾ Red⩾ 200 (Reynolds number) 2⩾ dij10 ( particle spacings)and 0. 1 ⩾ prRed2000 (Piclet number). The verified computer simulation results indicate that convection heat transfer parameters of interacting spherical particles deviate significantly from solitary spheres for all Reynolds and Piclet numbers.

ISSN:1040-7782    

DOI:10.1080/10407788908944699

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Laminar flow and heal transfer in annular passages with axially nonuniform inner tubes are obtained numerically. A characteristic feature of these passages is that the flow separates in the streamwise direction. An axisymmetric coordinate system with an algebraic transformation in the radial direction kas been used. Fully elliptic vorticity-slream function and energy equations in the transformed coordinates are solved using an iterative alternate direction implicit (ADI) method. In an annulus with a smooth blockage, the flow separates immediately downstream of the blockage at Reynolds numbers greater than 100. The main features of the flow are established at a Reynolds number of 1000. The pressure drop is drastic near the maximum constriction. The heat flux is also high in the constricted region. A sharp increase in the heat transfer occurs where the fluid reattaches itself to the wall. The increase in the total pressure drop is about an order of magnitude greater than that in the average Nusselt number.

ISSN:1040-7782    

DOI:10.1080/10407788908944700

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A numerical analysis has been made to examine the possible deviation of the instantaneous heat transfer to a growing spherical bubble from the quasi-steady heat transfer to a nongrowing bubble. It has been confirmed that the instantaneous Nusselt number has a negative dependency on the temperature difference or, more directly, on the bubble growth rate. But the degree of the dependency is much lower than that previously predicted. The significant dependency of Nusselt number on the temperature difference as demonstrated by some experimental works presumably resulted, for the most part, from some effect other than that of the bubble growth rale increasing with the temperature difference.

ISSN:1040-7782    

DOI:10.1080/10407788908944701

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This paper describes the use of the finite-element technique to solve problems of steady periodic heal conduction. The concept of a complex variable can be used to reduce the governing unsteady heat conduction equation to two noncoupled Poisson equations. The validity of the present method is confirmed with a one-dimensional problem for which an analytic solution exists. Numerical solutions for a three-dimensional problem are presented to illustrate the capability of the method.

ISSN:1040-7782    

DOI:10.1080/10407788908944702

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor