Begell House Inc.
Computational Thermal Sciences: An International Journal
CTS
1940-2503
7
5-6
2015
PREFACE: 6TH INTERNATIONAL SYMPOSIUM ON ADVANCES IN COMPUTATIONAL HEAT TRANSFER (CHT-15)
vi
10.1615/ComputThermalScien.2016017089
Yogesh
Jaluria
Department of Mechanical and Aerospace Engineering Rutgers-New Brunswick, The State University of New Jersey Piscataway, NJ 08854, USA
Zhixiong
Guo
Rutgers University
NUMERICAL STUDY ON FLOW AND CONVECTIVE HEAT TRANSFER OF AVIATION KEROSENE IN A VERTICAL MINITUBE AT SUPERCRITICAL PRESSURES
375-384
10.1615/ComputThermalScien.2015014473
Dan
Huang
Department of Energy Sciences, Lund University, Box 118, Lund SE-22100, Sweden; Department of Energy Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China
Zan
Wu
Department of Energy Sciences, Lund University, P.O. Box 118, Lund, SE-22100, Sweden
Bengt
Sunden
Division of Heat Transfer, Department of Energy Sciences, Lund University, P.O. Box 118,
SE-22100, Lund, Sweden
aviation kerosene
heat transfer
supercritical pressure
buoyancy effects
Convective heat transfer of aviation kerosene at supercritical pressures in a vertical upward tube with inner diameter 1.8 mm was numerically studied using the renormalization group k−ε turbulence model with enhanced wall treatment. The thermophysical and transport properties of the aviation kerosene at various temperatures were obtained by a 10-species surrogate and the NIST SUPERTRAPP software. The grid independence was first studied and numerical results were then compared with experimental data for validation. Effects of mass flow rate, heat flux, pressure, and inlet temperature on the heat transfer performance were investigated. Under flow conditions given in this work, the results show that the heat transfer coefficient increases with mass flow rate, heat flux, or inlet temperature, while an increase in inlet pressure reduces the heat transfer coefficient. The buoyancy force has little effect on heat transfer.
HEAT TRANSFER IN NATURAL CONVECTION WITH FINITE-SIZED PARTICLES CONSIDERING THERMAL CONDUCTANCE DUE TO INTER-PARTICLE CONTACTS
385-404
10.1615/ComputThermalScien.2016014791
Shintaro
Takeuchi
Department of Mechanical Engineering,
Osaka University, 2-1 Yamada-oka, Suita-city, Osaka 565-0871 Japan
Takaaki
Tsutsumi
Department of Mechanical Engineering,
Osaka University, 2-1 Yamada-oka, Suita-city, Osaka 565-0871 Japan
Katsuya
Kondo
Department of Mechanical Engineering,
Osaka University, 2-1 Yamada-oka, Suita-city, Osaka 565-0871 Japan; Tottori University, 4-101 Koyama-Minami, Tottori, 680-8552 Japan
Takeshi
Harada
Department of Mechanical Engineering, Osaka University, 2-1 Yamada-oka, Suita-city, Osaka 565-0871 Japan
Takeo
Kajishima
Department of Mechanical Engineering,
Osaka University, 2-1 Yamada-oka, Suita-city, Osaka 565-0871 Japan
multiphase flow
solid-dispersion
immersed solid object
heat transfer
thermal contact conduction
The heat transfer problem in solid-dispersed two-phase flow is numerically studied. Temperature gradient within the finite-sized particles and inter-particle heat flux due to collisions are considered, and those effects on the flow structure and heat transfer are discussed. The interaction between fluid and particles is treated by our original immersed solid approach. For the conjugate heat transfer problems, to satisfy the thermal condition at the fluid-solid interface, our interfacial heat flux model is employed. Also, the interfacial flux model is extended to incorporate the heat conduction due to inter-particle contacts, based on 2D and axisymmetric contact heat resistance solutions. The method is applied to 2D and 3D natural convection problems including multiple particles in a confined domain under relatively low Rayleigh numbers (104−106). Heat transfer and particle behaviors are studied for different solid volume fractions (up to about 50%) and heat conductivity ratios (solid to fluid) ranging between 10−3 and 103. Under high solid volume fraction conditions, the particles are observed to form densely concentrated regions, where heat flow tends to channel through the contacting points. In three-dimensional solid-dispersed flows, by decomposing the heat flux into the contributions of the convection and conduction, the change of the major heat transfer mode is studied for different solid volume fractions and conductivity ratios.
THERMAL STRATIFICATION ON NATURAL CONVECTION OVER AN INCLINED WAVY SURFACE IN A NANOFLUID SATURATED POROUS MEDIUM
405-415
10.1615/ComputThermalScien.2015014263
D.
Srinivasacharya
Department of Mathematics, National Institute of Technology, Warangal-506004,
India
P. Vijay
Kumar
Dept. of Mathematics, National Institute of Technology Warangal-506004, Telangana, India
natural convection
inclined wavy surface
thermal stratification
nanofluid
porous medium
The objective of this article is to study the effect of thermal stratification on natural convection in a nanofluid along an inclined wavy surface embedded in a porous medium. A coordinate transformation is employed to transform the complex wavy surface to a smooth surface. The governing equations are transformed into a set of partial differential equations using the nonsimilarity transformation and then the local similarity and nonsimilarity method is applied to obtain coupled ordinary differential equations. Now, these equations are solved using the successive linearization method. The present results are compared with previously published work and are found to be in very good agreement. The effects of thermal stratification parameter, Brownian motion parameter, thermophoresis parameter, amplitude of the wavy surface, angle of inclination of the wavy surface on the nondimensional velocity, temperature, nanoparticle volume fraction, and heat and nanoparticle mass transfer rates are studied and presented graphically.
BIFURCATION OF NATURAL CONVECTION FLOW IN AN INCLINED DIFFERENTIALLY HEATED CLOSED SQUARE CAVITY
417-425
10.1615/ComputThermalScien.2016014443
Nicholas
Williamson
Department of Mechanical Engineering, The University of Sydney, New South Wales 2006, Australia
Steven W.
Armfield
School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006, Australia
Michael P.
Kirkpatrick
School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia
Wenxian
Lin
James Cook University, School of Engineering, Townsville, QLD 4814, Australia
convection
numerical simulation
differentially heated cavity flow
traveling waves
stability
The natural convection flow in an inclined differentially heated cavity is investigated numerically with two-dimensional simulations at Rayleigh number Ra = 1 × 10 and Ra = 1 × 10 for Prandtl number Pr = 7.0. At θ = 0, the problem is the standard canonical differentially heated cavity flow with isothermal "hot" and "cold" vertical walls and with adiabatic horizontal walls. As the angle of inclination is increased, with the hot wall situated below the cold wall, the flow approaches an unstable Rayleigh−Bernard type flow. Below a critical angle the fully developed flow is steady and exhibits the same basic structure of the standard cavity flow. As the angle of inclination is increased, the flow undergoes a bifurcation so that the fully developed flow is unsteady and single mode. The bifurcation takes the form of traveling waves continually circulating the periphery of the cavity. These waves are supported by convectively unstable natural convection boundary layers on the heated/cooled walls and by attached plumes on the adiabatic walls. It is the establishment of these plumes coupling the opposing boundary layers which provides the mechanism for absolutely unstable flow.
SIMULATING PHASE CHANGE HEAT TRANSFER USING COMSOL AND FLUENT: EFFECT OF THE MUSHY-ZONE CONSTANT
427-440
10.1615/ComputThermalScien.2016014279
Ali C.
Kheirabadi
Department of Mechanical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
Dominic
Groulx
Mechanical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada, B3H 4R2
phase change heat transfer
natural convection
mushy-zone constant
numerical modeling
commercial software
This paper presents a numerical study aimed at understanding the impact of the mushy-zone constant, Amush, on simulated phase change heat transfer. This parameter is found in the Carman-Kozeny equation which is used in the enthalpy-porosity formulation for modeling natural convection driven phase change. The melting of dodecanoic acid inside a rectangular thermal storage unit was simulated in COMSOL 4.4 and FLUENT 15.0; with Amush and the melting temperature range, ΔT, being varied per study. The simulated melt front positions were directly compared to experimental results. Results showed that Amush is an important parameter for accurately modeling phase change heat transfer; in particular, high Amush values corresponded to slower melting rates and the smallest Amush values resulted in unphysical predictions of the melt front development. Additionally, it was concluded that Amush and ΔT are not independent of one another in their roles of accurately modeling the melting rate; different values of ΔT would require different values of Amush to achieve the same melt front development. However, certain combinations of Amush and ΔT do lead to an overall melt fraction progression for the overall process and are in line with the experimental results, although the numerically predicted movement of the melting interface in such cases is not always correlated to the experiment. Further efforts are required to identify ideal values for these parameters, as well as to determine the extent to which these parameters hold for different materials and physical setups. It is anticipated that this paper will lead to further discussion on the significance of the mushy zone as a numerical technique for accurately modeling phase change heat transfer.
VALIDATION OF A MULTIFIELD APPROACH FOR THE SIMULATIONS OF TWO-PHASE FLOWS
441-457
10.1615/ComputThermalScien.2016015855
Solène
Fleau
Electricite de France, R&D Division, Chatou, France; Laboratoire de Modélisations et Simulations Multi-Echelle, Université Paris-Est Marne-la-Vallée, France.
Stephane
Mimouni
Electricite de France, R&D Division, MFEE, 6 Quai Watier, 78400 Chatou, France
Nicolas
Merigoux
Electricité de France, R&D Division, Chatou, France
Stephane
Vincent
Laboratoire de Modélisations et Simulations Multi-Echelle, Université Paris-Est Marne-la-Vallée, France.
two-phase flows
multifield approach
drag force
interface sharpening
capillary effects
large bubble test cases
free surface
Safety issues in nuclear power plant involve complex bubbly flows. To predict the behavior of these flows, the two-fluid approach is often used. Nevertheless, this model induces a numerical diffusion of interfaces, which results in a poor accuracy in the calculation of the local parameters. Therefore, to simulate large interfaces such as slugs or free surfaces, interface tracking methods have been developed using the single-fluid model. In this paper, the two approaches have been coupled in the CMFD code NEPTUNE_CFD to simulate adiabatic separated flows. The averaged momentum balance equations are solved for each field and are followed by an artificial compression step, which fixes the interface thickness and ensures mass conservation. Moreover, since the two-fluid model defines a velocity per field in the whole computational domain, a drag force is used to couple the velocity of each field at the interface. This article proposes also a new formulation for this force, to take into account the physical properties of the flow. To validate this approach, an analytical test case with a static bubble has been simulated with a mesh refinement test. Then, the simulations of a rising bubble, an oscillating bubble, and the Kelvin-Helmholtz instability have been performed to highlight the effect of the modification of the drag force. Finally, model comparisons are proposed with the Kelvin-Helmholtz and the Rayleigh-Taylor instabilities.
A MODELING STUDY TO ANALYZE THERMAL AND MECHANICAL EFFECTS OF PULSED LASER IRRADIATION ON TISSUES
459-465
10.1615/ComputThermalScien.2016015252
Mohit
Ganguly
Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Department of Biomedical Engineering, Florida Institute of Technology, Melbourne, FL, USA
Kunal
Mitra
Department of Biomedical Engineering
Florida Institute of Technology
150 W University Blvd, Melbourne, FL, USA
pulsed infrared lasers
finite element modeling
bio-heat transfer
thermal dose
von-Mises stress
Pulsed lasers are known for their spatial and temporal specificity in delivering heat energy to the tissues. This is useful in the laser ablation treatment mechanism where damage to the healthy tissues is highly undesired. Pulsed laser irradiation on tissues leads to photothermal and photomechanical interactions, which result in damage to the irradiated zone. Cumulative effects of photothermal and photomechanical interactions lead to damage in the tissues affecting the healthy surrounding tissues. In this paper, the effects of both mechanisms are studied using a finite-element model. A three-layered model of the skin is considered which is irradiated using a focused Nd:YAG infrared laser beam. The finite-element solver COMSOL Multiphysics is used to simulate the thermal and mechanical interaction due to the laser irradiation. Thermal effects of irradiation are evaluated using the equivalent thermal dose administered to the tissue. The mechanical interaction is evaluated in terms of the stress generated in the tissue during the laser ablation damage. Results obtained are useful in characterizing the laser parameters such as repetition rate, laser power, and pulse width affecting the ablation process. This will enable optimizing the laser ablation process for a more effective treatment with minimum damage to surrounding tissues.
NUMERICAL STUDY OF HEAT TRANSFER ENHANCEMENT BY DEFORMABLE TWIN PLATES IN LAMINAR HEATED CHANNEL FLOW
467-476
10.1615/ComputThermalScien.2015014208
Rakshitha U.
Joshi
Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, India 400076
Atul K.
Soti
IITB-Monash Research Academy, Indian Institute of Technology Bombay, Mumbai, India 400076
Rajneesh
Bhardwaj
Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai, India 400076; IITB-Monash Research Academy, Indian Institute of Technology Bombay, Mumbai, India 400076
fluid-structure interaction (FSI)
computational fluid dynamics (CFD)
flow-induced deformation
heat transfer enhancement
immersed boundary method
Fluid-structure interaction (FSI) of thin flexible plates involving large-scale flow-induced deformation is presented as a potential heat transfer enhancement technique. An in-house, strongly-coupled FSI solver is employed in which flow and structural solvers are based on sharp-interface immersed boundary and finite-element methods, respectively. Twin deformable thin plates in a heated channel are considered with laminar pulsating flow. Numerical simulations show that the vortex ring past the plates sweeps higher sources of vorticity generated on the channel walls out into the downstream−promoting the mixing of the fluid. The moving plates assist in convective mixing, augmenting convection in bulk and at the walls; thereby reducing thermal boundary layer thickness and improving heat transfer at the channel walls. The thermal augmentation is quantified in terms of instantaneous Nusselt number at the wall. Results are presented for two limiting cases of thermal conductivity of the plate−an insulated plate and a highly conductive plate. We discuss the feasibility and effectiveness of deformable plates and discuss the effect of important problem parameters−Young's modulus, flow frequency, and Prandtl number−on the thermal augmentation.
TRANSIENT ANALYSIS OF HEAT TRANSFER IN PARALLEL SQUARED CHANNELS FOR HIGH TEMPERATURE THERMAL STORAGE
477-489
10.1615/ComputThermalScien.2016015327
Assunta
Andreozzi
Dipartimento di Ingegneria Industriale, Università degli studi di Napoli Federico II, P.le Tecchio 80, 80125, Napoli, Italy
Bernardo
Buonomo
Dipartimento di Ingegneria Industriale e dell'Informazione, Università degli
Studi della Campania "Luigi Vanvitelli," Aversa (CE), Italy
Oronzio
Manca
Dipartimento di Ingegneria Industriale e dell'Informazione, Università degli
Studi della Campania "Luigi Vanvitelli," Aversa (CE), Italy
Salvatore
Tamburrino
Dipartimento di Ingegneria Industriale e dell'Informazione, Seconda Universita di Napoli, Aversa, Italy; ENEA C.R. Bologna, Via Martiri di Monte Sole 4, 40129 Bologna, Italy
thermal storage
high temperature
honeycomb solid matrix
An investigation on honeycomb solid matrix systems employed for high temperature thermal storage is provided numerically considering two models in the transient regime. The two models are related to a direct model with multiple channels and a porous medium model. The system with parallel squared section channels is described by a conjugated convective-conductive model by coupling the governing equations for fluid and solid matrix. The porous medium is modeled by assuming a Brinkman-Forchheimer-extended Darcy model and the LTNE is assumed. The models for different number of parallel squared channels or pores per unit of length (PPU) are considered. The honeycomb system is considered as an anisotropic porous medium, and assuming that the thermal storage system is adiabatic in order to estimate fluid dynamic and thermal characteristics for different PPU values. The Ansys-Fluent code is used to solve numerically the governing equations for both models. Results in terms of solid and fluid temperature profiles are given for different PPU values and for both models; they show that the two models are in very good agreement. The main consequence is that a honeycomb system can be simulated as a porous medium allowing a simpler numerical simulation also for parallel channel systems with high PPU. It is found that for high PPU systems the charging time decreases and for assigned partial charging time an increase in stored thermal energy is detected increasing the PPU value.
EFFECTS OF FLAME STRUCTURE ON ENTRAINMENT CHARACTERISTICS OF A FIRE PLUME
491-500
10.1615/ComputThermalScien.2016014919
Hitoshi
Suto
Fluid Dynamics Sector, Civil Engineering Research Laboratory, Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-city, Chiba, 270-1194, Japan
Yasuo
Hattori
Fluid Dynamics Sector, Civil Engineering Research Laboratory, Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-shi,
Chiba, 270-1194, Japan
plume
entrainment
turbulent diffusion flame
large-eddy simulation
Large-eddy simulations of a fire plume with flames and a buoyant plume without flames were performed. The effects of the flame structure on the entrainment characteristics in the flame region of a plume were then examined through comparison between the two sets of numerical results. The effects of the flame structure on the plume characteristics were marked only in the continuous flame and the intermittent flame regions in the fire plume. The existence of flames increased the mean value of the entrainment coefficient, which corresponds to entrainment efficiency, and the probability density of a high entrainment coefficient. In particular, a feature of a fire plume that prevents the forming of a wide high-temperature area immediately above the fire source was suggested to increase the frequency of highly entraining motion.
BENCHTOP MICROREACTOR BUILT FOR DIAGNOSTIC DEPOSITION OF CU3BIS3 FOR USE IN PHOTOVOLTAIC DEVICES
501-513
10.1615/ComputThermalScien.2016015325
Joshua A.
Epstein
Materials Science and Engineering, Rutgers, 607 Taylor Road, Piscataway, New Jersey 08854, USA
Richard J.
Castellano
Mechanical and Aerospace Engineering, Rutgers, 98 Brett Road, Piscataway, New Jersey 08854, USA
Jerry W.
Shan
Mechanical and Aerospace Engineering, Rutgers, 98 Brett Road, Piscataway, New Jersey 08854, USA
Dunbar P.
Birnie, III
Materials Science and Engineering, Rutgers, 607 Taylor Road, Piscataway, New Jersey 08854, USA
COMSOL
chemical reactor design
controlled thermal gradient
Copper bismuth sulfide (CBS) is a material that could be used in future solar panels as a more cost effective replacement for silicon or other thin films. Multiple low-temperature solvothermal methods to make this material have been discovered. Efforts to utilize these syntheses in a custom-built benchtop reactor meant to deposit the material on fluorine-doped tin oxide (FTO) glass have been under way for some time. Recently, a second generation reactor design has been completed that solves many problems associated with our first reactor. The design was intended to promote uniform liquid flow across the FTO glass. This reactor was also built with a temperature gradient transverse to the liquid flow so that the optimal temperature for the deposition of CBS could be discovered. The designing and fabrication of this reactor will be covered, as well as preliminary results from our deposition experiments with Cu3BiS3.
2D PARTICLE MECHANICS SIMULATIONS ON EVOLUTION AND INTERACTIONS OF HEAT CHAINS AND FORCE NETWORKS UNDER STEADY-STATE CONDITIONS
515-526
10.1615/ComputThermalScien.2016015767
Gulsad
Kucuk
Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, New Jersey, 08854, USA
Marcial
Gonzalez
School of Mechanical Engineering Purdue University 585 Purdue Mall West Lafayette, Indiana 47907-2088, USA
Alberto M.
Cuitino
Department of Mechanical and Aerospace Engineering, Rutgers University, Piscataway, NJ, 08854, USA
thermomechanical coupling
heat networks
force networks
cross-property relation
granular materials
contact mechanics
Unlike continuum media, granular materials host an inhomogeneous distribution of contact networks, which results in an uneven distribution of loads inside the dense particulate assemblies. These structural arrangements play a critical role in determining the preferred paths of heat transport, due to the fact that thermal contact conductance is a function of the contact interfaces formed between particles. In spite of recent experimental and theoretical studies on the evolution of force chains, the formation of heat chains and the correlation between them still remain unclear. In this regard, a two-dimensional discrete model based on a particle mechanics approach is developed to unveil the characteristics of these microstructural arrangements, and the interactions between them under steady-state and equilibrium conditions. Thermally-assisted compaction of powders is a widely used manufacturing technique. Therefore, in this work, we model a two-dimensional configuration of randomly distributed spherical particles confined in a rigid die under mechanical and thermal loads. For this particular configuration, we study fundamental concepts such as formation of force and heat chains, evolution of force and heat distributions with respect to compaction parameters, and cross-property relation between normal force and heat transferred at the contact surfaces.
HEAT TRANSFER IN JACKETED VESSEL EQUIPPED WITH DOWN-PUMPING PITCHED BLADE TURBINE
527-537
10.1615/ComputThermalScien.2015014383
Avinash
Chandra
Department of Chemical Engineering, Thapar University, Patiala, INDIA
Harwinder
Singh
Department of Mechanical Engineering, Thapar University, Patiala, India
turbulent heat transfer
pitched blade turbine
Prandtl number
Nusselt number
Heat transfer to a Newtonian fluid in a jacketed vessel equipped with a down-pumping pitched blade turbine (PBT) has been numerically investigated. The turbine has six blades at 45° angles and the turbine is placed concentrically in a cylindrical vessel with a flat top and bottom. An incompressible Newtonian fluid of constant density and viscosity has been considered. The cylindrical wall of the vessel is maintained at constant wall temperature with the help of an outer jacket. The governing momentum and energy equations were numerically solved to obtain the flow and heat transfer fields. The detailed flow and heat transfer fields have been explored for Reynolds number, Re = 7.2 × 104, and Prandtl number in the range 0.71 ≤ Pr ≤ 50. The obtained flow and heat transfer fields are presented as velocity contours, pressure contours, and isotherm profiles at various sections. It is observed that the velocity gradient is higher in the vicinity of the turbine as compared to the vessel wall. In the vertical plane, the velocity is found to be maximum just below the turbine because of the down-pumping of the fluid. The observation of isotherm profiles shows that the temperature gradient is very large near to the vessel wall and small in the vicinity of the turbine. An almost uniform temperature profile was obtained at the highest Prandtl number of 50. The degree of thermal mixing and heat transfer coefficient increases with increasing value of Prandtl number. The area-weighted average value of the Nusselt number shows positive dependence on the Prandtl number. A functional relationship within the average Nusselt number and Prandtl number has been proposed for the present configuration and the operating conditions.
CONTENTS VOLUME 7, 2015
539-544
10.1615/ComputThermalScien.v7.i5-6.150