Showing papers by "Arun S. Mujumdar published in 1985"
214 citations
TL;DR: In this paper, a numerical method capable of handling three-dimensional transport processes is devised to model the developing steady laminar flow and heat transfer to power-law fluids flowing in ducts of arbitrary but uniform cross section.
Abstract: A numerical method capable of handling three-dimensional transport processes is devised to model the developing steady laminar flow and heat transfer to power-law fluids flowing in ducts of arbitrary but uniform cross section. The governing equations are the general momentum and energy equations parabolized in the axial direction and as such are applicable to flow systems with a predominant flow direction. An orthogonal body-fitted coordinate system is employed to handle complex cross-sectional geometries. The transformed equations are discretized in a finite-difference form, and the resulting algebraic equations are solved by line successive over-relaxation (SOR). For the purpose of testing the algorithms and the computer code, solutions are computed for the well-known case of a Newtonian fluid in a square duct. Excellent agreement with available numerical and experimental results is obtained. The versatility of the code is demonstrated by presentation of flow and heat transfer results for power-law flui...
25 citations
TL;DR: In this paper, a computational model is presented to predict the flow and heat transfer characteristics of a single, semi-confined turbulent jet impinging normally on an impermeable isothermal planar surface.
Abstract: Results of a computational model are presented to predict the flow and heat transfer characteristics of a single, semi-confined turbulent jet impinging normally on an impermeable isothermal planar surface. A two-equation model of turbulence was employed. Effects of jet Reynolds number, nozzle-to-surface spacing and the turbulence level at the nozzle plane were examined numerically. Predicted results compare favorably with available data although further refinement of the turbulence model is needed for impingement-type flows.
16 citations
TL;DR: In this paper, the authors examine the problem of numerical solutions to the classical Graetz problem in the entrance region of pipes and attempt to provide plausible explanation for the discrepancy in the Nusselt number.
15 citations
TL;DR: In this article, a steady laminar boundary-layer analysis of combined heat and mass transfer characteristics in free convection around a horizontal cylinder has been carried out by two approximate methods, viz., local similarity and local nonsimilarity approaches.
Abstract: Steady laminar boundary-layer analysis of combined heat and mass transfer characteristics in free convection around a horizontal cylinder has been carried out by two approximate methods, viz., local similarity and local nonsimilarity approaches. Numerical results of the local Nusselt number, the local Sherwood number, and local surface shear stress are presented, along with the dimensionless thermal, mass fraction, and momentum boundary-layer thicknesses in tabular form. The parameter ranges are chosen to encompass most commonly occurring circumstances in natural and technological processes.
12 citations
TL;DR: In this article, a high sensitivity, fast response heat flux sensor was developed for heat flux measurement at a moving surface subjected to rapidly fluctuating heat flux, which measured instantaneous surface temperature with a resolution of about 0.002°C at sampling speeds up to 5000 s−1.
9 citations
TL;DR: In this paper, the dimensionless non-linear coupled boundary-layer equations embody the following parameters: (1) Pr, the Prandtl number, (2) Sc, the Schmidt number and (3) R, the ratio of the concentration to the thermal buoyancy forces.
Abstract: Laminar free convection around a long porous limiting cylindrical surface arising from the buoyancy forces created by temperature as well as by transpiration-induced concentration gradients is investigated. All the fluid properties except for the temperature and concentration-dependent body forces are assumed to be constant in the analysis. The dimensionless non-linear coupled boundary-layer equations embody the following parameters: (1) Pr, the Prandtl number, (2) Sc, the Schmidt number and (3) R, the ratio of the concentration to the thermal buoyancy forces. Numerical results for the local Nusselt number, the local wall shear stress and the local Sherwood number are displayed graphically for the transpiration-induced convective diffusion of hydrogen, water vapour and naphthalene into an air-saturated porous medium. The dimensionless thermal, concentration and momentum boundary layer thicknesses, along with the cumulative tangential mass flow rate are given in tabular form. The analysis covers a wide range of blowing rates.
8 citations
TL;DR: In this article, a steady laminar binary mixed convection flow along a vertical circular cone under the combined buoyancy effects of thermal and species diffusion is studied analytically.
Abstract: Steady laminar binary mixed convection flow along a vertical circular cone under the combined buoyancy effects of thermal and species diffusion is studied analytically The analysis is confined to mass diffusion processes with low concentration levels In the analysis the surface of the cone is assumed to be at a uniform temperature and uniform concentration Numerical results for the local Sherwood number, local Nusselt number and local friction factor are presented Representative temperature, concentration and velocity profiles are also shown The analysis covers the diffusion of common gases and vapours into air Considerations are given to the situations where the buoyancy forces assist and oppose the forced convection flow for various possible combinations of the thermal and species diffusion processes
7 citations
TL;DR: In this paper, the authors worked out analytical solutions to the extended Graetz problem with viscous dissipation and internal heat generation using the variational method and assessed the reliability of this method by comparing these solutions with those obtained from the series expansion and numerical methods.
Abstract: Analytical solutions to the extended Graetz problem with viscous dissipation and internal heat generation are worked out using the variational method. The reliability of this method is assessed by comparing these solutions with those obtained from the series expansion and numerical methods.
5 citations
TL;DR: In this article, the results of an extensive flow visualization study to examine the particle-free air gap formation around horizontal, rigidly-mounted circular cylinders in a two dimensional vibrated bed are presented.
Abstract: Pressure drop measurements and results of an extensive flow visualization study to examine the particle-free air gap formation around horizontal, rigidly-mounted circular cylinders in a two dimensional vibrated bed, are presented. Effects of particle size and surface stickiness as well as other key operating parameters viz. aeration rate and vibrational frequency were examined for single as well as multiple cylinder configurations in staggered and in-line arrangements.
On presente des mesures de pertes de charge et les resultats d'une vaste etude de visualisation d'ecoulement, pour examiner la formation d'un espace d'air, libre de particules, autour de cylindres circulaires horizontaux, montes d'une maniere rigide dans un lit vibre a deux dimensions, On a examine les effets des dimensions des particules et d'une surface collante ainsi que d'autres parametres-cles du fonctionnement tels que la vitesse d'aeration et la frequence vibrationnelle, pour des configurations a un ou plusieurs cylindres alignes ou echelonnes.
5 citations
01 Jan 1985
TL;DR: In this paper, an experimental results were presented and discussed for heat transfer for single tubes mounted horizontally and rigidly in a vibrated bed of glass ballotini and molecular sieve particles.
Abstract: Experimental results are presented and discussed for heat transfer for single tubes mounted horizontally and rigidly in a vibrated bed of glass ballotini and molecular sieve particles. A dramatic increase in the heat transfer rate was found to occur during removal of surface moisture for molecular sieve particles. Below the critical moisture content the transfer rate approaches rapidly that for completely dry beds under identical operating conditions. Effects of vibrational amplitude/acceleration, aeration rate and particle size are also presented.
TL;DR: In this article, an analytical study is carried out to examine the combined heat and mass transfer characteristics under mixed convective flow along the external surface of a vertical circular cone, where the surface of the cone is subjected to uniform heat andmass fluxes.
Abstract: An analytical study is carried out to examine the combined heat and mass transfer characteristics under mixed convective flow along the external surface of a vertical circular cone. The analysis is limited to processes in which diffusion-thermo and thermo-diffusion effects can be neglected as well as limited to cones with large apex angles whereby the radial curvature effects can be neglected. The surface of the cone is subjected to uniform heat and mass fluxes. Numerical results of the local Sherwood number, the local Nusselt number and the local friction factor are obtained from the local similarity as well as local nonsimilarity approaches. Consideration is given to situations where the net buoyancy force assists and opposes the forced flow. Calculations are confined to diffusion of common gases and vapors into air.
TL;DR: In this article, the combined heat and mass transfer characteristics of laminar free convection flow about a sphere are studied analytically, and the analysis assumes negligible interfacial velocities due to mass diffusion as well as insignificant diffusion-thermo and thermo-diffusion effects.
Abstract: Combined heat and mass transfer characteristics of laminar free convection flow about a sphere are studied analytically. The analysis assumes negligible interfacial velocities due to mass diffusion as well as insignificant diffusion-thermo and thermo-diffusion effects. The surface of the sphere is assumed to be at a uniform temperature and a uniform concentration. Boundary layer equations for the system are solved for the specific cases of convective diffusion of water vapor and naphthalene into air by the local similarity and the local nonsimilarity approaches. Numerical results of the local Sherwood number, the local Nusselt number and local wall shear stress obtained from the local nonsimilarity solutions are reported in a tabular form and the local similarity results are displayed graphically. In the analysis the cases of aiding and opposing thermal and concentration buoyancy forces are considered. Cumulative mass flow rates along with the dimensionless representative profiles of temperature, concentration and tangential velocities are presented for various combinations of parameters.
TL;DR: In this article, the problem of combined heat and mass transfer in laminar free convection along a vertically rotating plate subjected to a uniform heat flux and/or a uniform mass flux is studied analytically.
Abstract: The problem of combined heat and mass transfer in laminar free convection along a vertically rotating plate subjected to a uniform heat flux and/or a uniform mass flux is studied analytically. The governing non-dimensional nonlinear coupled partial differential equations are solved by local similarity and local nonsimilarity approach. Numerical results for the local Nusselt number, the local Sherwood number and the local wall shear stress for the convective-diffusion of hydrogen, water vapor and naphthalene into the air are presented in tabular forms. The analysis extends the range both when the concentration buoyancy force assists as well as opposes the thermal buoyancy force.