Begell House Inc.
Heat Transfer Research
HTR
1064-2285
44
2
2013
UNSTEADY HEAT TRANSFER IN AN ENCLOSURE WITH A TIME-PERIODIC ROTATING CYLINDER
145-161
Habibis
Saleh
School of Mathematical Sciences, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor, Malaysia
Ishak
Hashim
School of Mathematical Sciences & Solar Energy Research Institute, Faculty of Science
& Technology, Universiti Kebangsaan Malaysia 43600 UKM Bangi, Selangor DE, Malaysia
Unsteady mixed convection heat transfer in a differentially heated square enclosure is studied in this article. A conductive circular with rotational speed varying periodically with time is embedded in the center of the enclosure. The governing equations are modeled in the COMSOL, with a partial differential equation (PDE) solver being based on the Galerkin finite element method (GFEM). The governing parameters considered are the rotary amplitude, −1000 ≤ AΩ ≤ 1000, the rotary frequency, 0 ≤ FΩ ≤ 300Π, the cylinder radius, 0 ≤ R ≤ 0.2, and the thermal conductivity ratio, 0.5 ≤ Kr ≤ 10. It was found that the recirculating cells exist for a positive rotary amplitude and it increases with the rotational speed. Fast rotation and a high frequency combined with a low thermal conductivity ratio was found to be most effective in enhancing the performance of the overall heat transfer rate.
MIXED CONVECTION HEAT AND MASS TRANSFER IN INCLINED CIRCULAR DUCTS
163-193
Aicha
Bouhezza
Department of Sciences of Matter, Faculty of Science, University of 20 Aout 55-Skikda, Skikda, 21000, Algeria
Omar
Kholai
Department of Mechanical Engineering, University of Mentouri Constantine, Constantine, 25000, Algeria
Saadoun
Boudebous
Department of Mechanical Engineering, University of Mentouri Constantine, Constantine, 25000, Algeria
Zoubir
Nemouchi
Laboratoire d'Energetique Appliquee et de Pollution, Université des Frèses Mentouri, Constantine, Algeria
The effects of thermal and solutal buoyancy forces and inclination angle on the development of laminar mixed convection in a circular inclined duct with uniform heat flux and uniform concentration at the fluid−solid interface on a part of its length was investigated. A three-dimensional elliptic model for three directions was used. The hydrodynamic, temperature, and concentration fields and the circumferentially averaged Nusselt and Sherwood numbers are presented for different combinations of two Richardson numbers and inclination angles. The results show that the velocity, temperature, and concentration distributions, as well as the Nusselt and Sherwood numbers, depend on the thermal Richardson and solutal Richardson numbers and the inclination angle. For a vertical duct with ascending flow, the thermal and solutal buoyancy forces enhance the heat and mass transfer. On the other hand, for a descending flow these forces reduce the heat and mass transfer, decelerate the fluid close to the wall, and produce flow reversal close to the duct wall.
MAGNETOCONVECTION OF AN ELECTRICALLY CONDUCTING FLUID IN AN ANNULAR SPACE BETWEEN TWO ISOTHERMAL CONCENTRIC SQUARES
195-214
Sofen K.
Jena
Department of Flows and Materials Simulation, Fraunhofer Institute for Industrial Mathematics (ITWM), Kaiserslautern, Germany, D-67663; Department of Mechanical Engineering, Jadavpur University, Kolkata, India-700032
Swarup Kumar
Mahapatra
Indian Institute of Technology Bhubaneswar
Amitava
Sarkar
Department of Mechanical Engineering, Jadavpur University, Kolkata, India-700032
The present study is focused on the analysis of thermogravitational convection of an electrically
conducting fluid in a rectangular annular space under the influence of an externally imposed timeâ€independent uniform magnetic field. The inner sides of the annulus are exposed to a higher temperature, whereas the outer sides are at lower temperature. Interest in such a study comes from its application in various scientific and industrial processes. Annular casings are made around many electrical devices. Heat generated by the devices is convected in the annular space, which occurs due to the thermogravitational effect and is affected by the imposed electromagnetic
field. The solution is done by control volume integration. Modified MAC method is used for the numerical solution of governing equations. The gradient dependent consistent hybrid upwind scheme of second order (GDCHUSSO) is used for discretization of the convective terms. Comprehensive
studies on controlling parameters that affect the flow and heat transfer characteristics are studied. Physics of the phenomenon is understood from the provided flowlines and isotherms. The results of the parametric study are provided in graphical and tabular form.
SOLUTIONS FOR MHD NATURAL CONVECTION FLOW OF A PARTICULATE SUSPENSION THROUGH A VERTICAL CHANNEL WITH ASYMMETRIC THERMAL BOUNDARY CONDITIONS
215-243
Ali J.
Chamkha
Department of Mechanical Engineering, Prince Sultan Endowment for Energy and
Environment, Prince Mohammad Bin Fahd University, Al-Khobar 31952, Kingdom of Saudi
Arabia; RAK Research and Innovation Center, American University of Ras Al Khaimah, United Arab Emirates, 10021
Seham S.
Al-Rashidi
Manufacturing Engineering Department, The Public Authority for Applied Education and Training, P. O. Box 42325, Shuweikh 70654, Kuwait
A continuum model for two-phase (fluid/particle) flow induced by natural convection is developed and applied to the problem of steady natural convection MHD flow of a particulate suspension through an infinitely long vertical channel in the presence of heat generation or absorption effects. The walls of the channel are heated asymmetrically such that one of the channel walls is maintained at a constant heat flux, while the other is maintained at a constant temperature. The boundary conditions borrowed from the rarefied gas dynamics are employed for the particle-phase wall velocity conditions. Various closed-form solutions for different special cases are obtained. A parametric study of some physical parameters involved in the problem is done to illustrate the influence of these parameters on the flow and thermal aspects of the problem.