Showing papers by "Suhas V. Patankar published in 1994"

Finite volume method for radiation heat transfer

Abstract: This chapter presents a finite-volume (FV) method for computing radiation heat transfer processes The main ingredients of the calculation procedure were presented by Chai et al [1] The resulting method has been tested, refined and extended to account for various geometrical and physical complexities

Finite volume radiative heat transfer procedure for irregular geometries

Abstract: A finite volume method for irregular geometries is presented in this article. The capability of the procedure is tested using five test problems. In these tests, transparent, absorbing, emitting, and anisotropically scattering media are examined. The solutions indicate that the finite volume method is a viable solution procedure for radiative heat transfer processes.

Treatment of irregular geometries using a Cartesian coordinates finite-volume radiation heat transfer procedure

Abstract: This article presents a blocked-off-region procedure to model radiative transfer in irregular geometries using a Cartesian coordinates finite-volume method (FVM). Straight-edged, inclined and curved boundaries can be treated. It is capable of handling participating or transparent media enclosed by black or reflecting walls. With this procedure, irregular geometries can be specified through the problem specification portion of the program. Four test problems are used to show that the procedure is capable of reproducing available results for inclined and curved walls, transparent, nonscattering, and anisotropically scattering media.

Evaluation of Spatial Differencing Practices for the Discrete-Ordinates Method

Abstract: Three popular spatial differencing practices for the discrete ordinates method are examined in detail for a basic two-dimensional Cartesian coordinates problem. These differencing schemes are 1) positive, 2) step, and 3) diamond schemes. The diamond scheme is shown to produce negative intensities under certain conditions irrespective of the number of control volumes employed, requiring some form of negative intensity fix-up. In absorbing-emitting or absorbing-emitting-scattering media, grid refinement can result in negative intensities when the diamond scheme is used. The diamond scheme and a positive scheme, which sets the negative intensities encountered in the diamond scheme to zero or very small number for purely absorbing media, can also produce physically unrealistic overshoots. The step scheme, although not considered as accurate as the diamond scheme, gives physically realistic results for the basic problem considered. Further evaluation of Fiveland's positive conditions, and variable weight and exponential-type schemes indicate a need for alternate spatial differencing schemes that describe the physics of radiative heat transfer more accurately.

Improved Treatment of Scattering Using the Discrete Ordinates Method

Abstract: A finite volume method (FVM) is presented in this article. This procedure can be used to model transparent, absorbing, emitting, and anisotropically scattering media. A procedure to capture collimated beam is also presented. The FVM is applied to six test problems, and the results compared favorably against other published results. The test problems include two- and three-dimensional enclosures with participating media, collimated incidence, and heat generation. The efficiency of the FVM procedure is also investigated using a three-dimensional test problem.

Block-correction-based multigrid method for fluid flow problems

Abstract: A coupled-point solution procedure employing a multilevel correction strategy is developed and test results are presented in this article. The method is based on the principle of deriving the coarse-grid discretization equations from the fine-grid discretization equations. The adaptive scheme is applied to the sample problems of laminar flow in lid-driven square and cubic cavities and flow over a backward-facing step. The study demonstrates that the multigrid method is robust and rapidly convergent, resulting in improvement in CPU requirements by a factor of approximately S to 15 compared to the sequential signal-grid SIMPLER procedure. The performance of procedure improves, in comparison to the SIMPLER, as the number of grid points increases.

Prediction of Turbulent Flow and Heat Transfer in a Rotating Square Duct With a 180 deg. Bend

Abstract: This paper reports the results of a numerical study on the fluid flow and heat transfer in a rotating square duct with 180 deg. bend. The computations are based the standard k-e turbulence model with wall functions. At a fixed Reynolds number, results have been obtained over a range of Rotation numbers and coolant-to-wall temperature ratios. These results reflect the complex interaction of Coriolis forces, buoyancy forces, and curvature effects. For the outward leg, rotation causes the heat transfer enhancement on the trailing surface and degradation on the leading surface. However, in the inward leg, there is heat transfer degradation on the trailing surface and enhancement on the leading edge. The buoyancy forces cause further degradation in the heat transfer on the leading surface and enhancement on the trailing surface of the outward leg.Copyright © 1994 by ASME

Numerical analysis of water spray system in the entrance region of a two-dimensional channel using lagrangian approach

Abstract: A numerical study of a turbulent gas-liquid droplet flow is presented using the Lagrangian approach for the discrete phase and the Eulerian approach for the continuous phase. The spray nozzle is mounted on the wall of a two-dimensional plane channel, The influence of different directional angles as well as the angle of spray on the velocity and temperature field of the main phase are studied. Three sine categories are used to model the spray with the mean mass diameter of I mm, Two different spray angles are defined, namely 10° and 60°, The average directional angle varies (measured from the wall) from 60° to 120°.

Laminar mixed convection in a horizontal semicircular duct with axially nonuniform thermal boundary condition on the flat wall

Abstract: Mixed convection in a horizontal semicircular duct is studied numerically. An axially nonuniform temperature distribution is prescribed on the flat wall, with the midsection at a higher temperature than the end sections. The full three-dimensional Navier-Stokes equations coupled with the energy equation are solved using a control-volume method. Results are presented for two values of the Grashof number (Gr = 5 [times] 10[sup 3] and 5 [times] 10[sup 4]) and three values of the Reynolds number (Re = 10, 20, 50), for a gas with Prandtl number of 0.7. For flow conditions characterized by a large value of the parameter Gr/R[sup 2], the buoyancy forces give rise to both longitudinal and transverse rolls in the duct, which cause nonuniformities in the heat flux distribution. The secondary flow pattern and the heat flux distribution on the heated section of the flat wall are strongly dependent on the thermal boundary condition on the curved wall of the duct.