Begell House Inc.
Computational Thermal Sciences: An International Journal
CTS
1940-2503
1
1
2009
Editorial
1
Graham
de Vahl Davis
University of New South Wales, Kensington, NSW, Australia
Ivan Vladimirovich
Egorov
Central Aerohydrodynamic Institute (TsAGI), 1, Zhukovsky Str., Zhukovsky,
Moscow Region, 140180, Russian Federation
Welcome to Volume 1 Number 1 of Computational Thermal Sciences
Computational Thermal Sciences is a new peer reviewed international journal designed to provide a forum for the exposure and exchange of ideas, methods and results in all areas of thermal sciences: computational thermodynamics, fluid dynamics, heat transfer and mass transfer in solids, liquids and gases, with applications in areas such as energy, materials processing, manufacturing and the environment. All modes of heat and mass transfer will be included: conduction, convection, diffusion, radiation and phase change. Topics to be covered will also include the laws of thermodynamics, the thermal properties of substances, engine and refrigeration cycles and combustion.
Papers on all aspects — both fundamental and applied — will be welcome: on the one hand the development of new mathematical methods and computational algorithms, and on the other the application of new or existing methods to the solution of problems in the thermal sciences. Reports of experimental studies undertaken in conjunction with computational work are encouraged. The assessment of the accuracy of computational solutions through verification (examining and limiting errors associated with discretization and with the computational solution methods adopted) and validation (quantification of errors in the physical models used) are essential parts of any computational study, and authors will be expected to examine these aspects.
Some of the papers in this issue are expanded or modified versions of papers originally presented at CHT-08, an International Symposium on Computational Heat Transfer, Marrakech Morocco, May 2008, which was organised by the International Centre for Heat and Mass Transfer. We are pleased to continue the relationship between Begell House and ICHMT, but of course this journal will welcome original research papers from all sources.
Volume 1 Number 1 of Computational Thermal Sciences is dedicated to the memory of Eddie Leonardi, formerly Associate Editor, who tragically died at an early age on December 14, 2008.
THERMAL RADIATION MODELING IN NUMERICAL SIMULATION OF MELT-COOLANT INTERACTION
1-35
Leonid A.
Dombrovsky
Joint Institute for High Temperatures, 17A Krasnokazarmennaya Str., Moscow,
111116, Russia; Tyumen State University, 6 Volodarsky Str., Tyumen, 625003, Russia
M. V.
Davydov
Electrogorsk Research & Engineering Center on NPP Safety, Saint Constantine 6,142530, Electrogorsk, Moscow region, Russia
P.
Kudinov
Division of Nuclear Power Safety, Royal Institute of Technology (KTH), Roslagstullbacken 21, Alba Nova, Stockholm 10691, Sweden
This paper is concerned with radiation heat transfer modeling in multiphase disperse systems, which are formed in high-temperature melt-coolant interactions. This problem is important for complex interaction of the core melt with water in the case of a hypothetical severe accident in light-water nuclear reactors. The nonlocal effects of thermal radiation due to the semitransparency of water in the visible and near-infrared spectral ranges are taken into account by use of the recently developed large-cell radiation model (LCRM) based on the spectral radiation energy balance for single computational cells. In contrast to the local approach for radiative heating of water by particles (OMM—opaque medium model), the LCRM includes radiative heat transfer between the particles of different temperatures. The regular integrated code VAPEX-P, intended to model the premixing stage of FCI, was employed for verification of the LCRM in a realistic range of the problem parameters. A comparison with the OMM and the more accurate P1 approximation showed that the LCRM can be recommended for the engineering problem under consideration. The effects of the temperature difference in solidifying particles are analyzed by use of the recently suggested approximation of transient temperature profile in the particles. It is shown that the effect of the temperature difference on heat transfer from corium particles to ambient water is considerable and should not be ignored in the calculations. An advanced computational model based on the LCRM for the radiation source function and subsequent integration of radiative transfer equation along the rays is also discussed.
MODELING OF A TURBULENT ETHYLENE/AIR JET FLAME USING HYBRID FINITE VOLUME/MONTE CARLO METHODS
37-53
Ranjan S.
Mehta
Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Anquan
Wang
GE Global Research Center, One Research Circle, Niskayuna, NY 12309; Department of Mechanical Engineering, Pennsylvania State University, University Park, PA 16802, USA
Michael F.
Modest
School of Engineering, University of California, Merced, USA
Daniel C.
Haworth
Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
Detailed modeling of an experimental ethylene/air jet flame is undertaken using the joint composition probability distribution function (PDF) method for gas-phase kinetics coupled with detailed models for soot formation and radiation from the flames. The gas-phase kinetics is modeled using a reduced mechanism for ethylene consisting of 33 species and 205 elementary reactions. The soot formation is modeled using the method of moments with a simplified nucleation mechanism and modified surface-HACA (Hydrogen abstraction acetylene addition) mechanism for surface growth and oxidation. The soot formation is coupled directly with a transported PDF approach to account for turbulence-chemistry interactions in gas-phase chemistry and the highly nonlinear soot formation processes. Radiation from soot and combustion gases is accounted for by using a photon Monte Carlo method coupled with nongray properties for soot and gases. Soot particles are assumed to be small, and scattering effects are neglected. Turbulence-radiation interactions are captured accurately. Simulation results are compared to experimental data, and also with less CPU-intensive radiation calculations using the optically thin approximation.
NUMERICAL STUDY OF THERMAL CHAOTIC MIXING IN A TWO ROD ROTATING MIXER
55-73
Yves
Le Guer
Laboratoire des sciences de l’ingénieur Appliquées a la Mécanique et au génie Electrique (SIAME), Université de Pau et des Pays de l’Adour (UPPA), IFR, rue Jules Ferry, BP 7511, 64075 Pau Cedex, France
Kamal
El Omari
Laboratoire des sciences de l’ingénieur Appliquées a la Mécanique et au génie Electrique (SIAME), Université de Pau et des Pays de l’Adour (UPPA), IFR, rue Jules Ferry, BP 7511, 64075 Pau Cedex, France
In this paper, a numerical study of a chaotic mixing process that involves a highly viscous fluid is presented. The investigated mixer is composed of two circular rods maintained vertically inside a cylindrical tank. The tank and rods are heated and can rotate around their revolution axes. Chaotic flows are obtained by imposing a temporal modulation of the rotational velocity. Unsteady equations for the conservation of momentum and energy are solved by using a pressure-based code. This code has a finite volume formulation applied to unstructured hybrid grids. The efficiency of the mixer is analyzed by focusing on the quantity of thermal energy supplied to the fluid and on the quality of the temperature homogenization. The influence of different parameters is analyzed: the type of modulation, the size of its period, the direction of rotations, and the eccentricity of the rods.
NUMERICAL STUDY ON FLOW BOILING HEAT TRANSFER OF A REFRIGERANT MIXTURE IN HORIZONTAL TUBES UNDER A VARIED HEAT FLUX BOUNDARY CONDITION
75-103
Balakrishnan
Raja
IIITD&M Kancheepuram
Dhasan Mohan
Lal
R&AC Division, Department of Mechanical Engineering, College of Engineering, Guindy, Anna University, Chennai − 600 025, India
Rajagopal
Saravanan
R&AC Division, Department of Mechanical Engineering, College of Engineering, Guindy, Anna University, Chennai-600 025, India
A mathematical model has been developed to simulate the in-tube flow boiling heat transfer process of a refrigerant mixture under a variable heat flux boundary condition. The one-dimensional steady-state evaporation model is focused at a low heat flux and mass flow rate condition that is found in evaporator tubes of supermarket refrigerators and deep freezers. The governing equations are simplified to capture the physics of the stratified two-phase flow of the liquid and vapor phases during the boiling process. Finite volume formulation is used to solve the continuity, momentum, and energy equations. The present work is used to investigate the distributions of the temperature, heat transfer coefficient, heat flux, and void fraction of the refrigerant along the length of the evaporator tube. The simulation results from the model are verified with experimental results and the deviation is within acceptable limits.