Begell House Inc.
Computational Thermal Sciences: An International Journal
CTS
1940-2503
12
1
2020
THREE-DIMENSIONAL NATURAL CONVECTION PHENOMENA AROUND A UNIFORMLY HEATED CUBICAL BODY LOCATED AT THE CENTER OF A SPHERICAL ENCLOSURE
1-20
10.1615/ComputThermalScien.2020028346
Hedia
Welhezi
Laboratory of Physics of Fluids, Physics Department, Faculty of Science of Tunis, University of
Tunis El-Manar, 2092 El-Manar 2, Tunis, Tunisia
Nader
Ben-Cheikh
Laboratory of Mechanic of Fluids, Physics Department, Faculty of Sciences of Tunis, University of Tunis El-Manar, 2092 El-Manar II, Tunis, Tunisia
Brahim
Ben-Beya
Laboratory of Physics of Fluids, Physics Department, Faculty of Science of Tunis, University of
Tunis El-Manar, 2092 El-Manar 2, Tunis, Tunisia
spherical enclosure
natural convection
three-dimensionality
This investigation addresses a systematic numerical method based on the finite volume method and a full multigrid technique to study three-dimensional natural convection phenomena around a heated cube placed inside a concentric air-filled spherical enclosure. In this work, we observed the flow structures and heat transfer characteristics in the enclosure according to the variation of the Rayleigh number. The computation is performed for Rayleigh numbers ranging from 102 to 106, and the Prandtl number is of Pr = 0.71. Typical sets of streamlines and isotherms are presented to analyze the intricate circulatory flow patterns set up by the buoyancy force of the fluid. The variation of the local and surface-averaged Nusselt numbers at the inner hot cube wall are also presented to exhibit the overall heat transfer characteristics inside the enclosure. It was found that, when the Rayleigh numbers are low, the isotherms are approximately parallel and the conduction is the dominant heat transfer mode; whereas, as the Rayleigh number increases, buoyancy-induced convection heat transfer becomes dominant and the isotherms are squeezed because of the stronger convection effects. Results also indicate that an optimal average heat transfer rate is obtained for Rayleigh number set to 102 for both cases of the spherical enclosure and inner cube.
INFLUENCE OF VARIABLE LIQUID PROPERTIES ON MAGNETOHYDRODYNAMIC FLOW AND HEAT TRANSFER OF A CASSON LIQUID OVER A SLENDER ROTATING DISK: NUMERICAL AND OPTIMAL SOLUTION
21-39
10.1615/ComputThermalScien.2019029098
Hanumesh
Vaidya
Department of Mathematics, SSA Government First Grade College (Autonomous),
Ballari-583101, Karnataka, India
K. V.
Prasad
Department of Mathematics, Vijayanagara Sri Krishnadevaraya University Jnana Sagara Campus,Vinayaka Nagar Cantonment, Ballari-583 105, Karnataka,
India
Kuppalapalle
Vajravelu
Department of Mathematics, University of Central Florida, Orlando, Florida 32816, USA
B. Srikantha
Setty
Department of Mathematics, VSK University, Vinayaka Nagar, Ballari-583 105, Karnataka,
India
Oluwole Daniel
Makinde
Faculty of Military Science, Stellenbosch University, Private Bag X2, Saldanha 7395, South
Africa
rotating disk
variable thickness
variable liquid properties
optimal homotopy analysis method
The present work deals with magnetohydrodynamic (MHD) flow and heat transfer of a Casson liquid over a rotating disk with variable thickness. The effects of velocity slip, convective boundary condition, viscous dissipation, and internal heat generation/absorption are considered. The transport properties of the fluid, for example, viscosity dissipation and thermal conductivity, vary with temperature. The governing nonlinear partial differential equations of the problem are reduced to a system of nonlinear ordinary differential equations by the von Karman approach and are solved numerically as well as semi-analytically. The numerical results are compared with previous studies for a special case and found to be in excellent agreement. Impacts of the pertinent parameters on the velocity components and the temperature field are graphically presented and analyzed in detail. The temperature distribution gets augmented for raising the values of viscous dissipation; variable thermal conductivity, and heat source/sink parameter.
NUMERICAL STUDY OF BUBBLE GROWTH AND HEAT TRANSFER IN MICROCHANNEL USING DYNAMIC CONTACT ANGLE MODELS
41-54
10.1615/ComputThermalScien.2020021272
Ayyaz
Siddique
Department of Mechanical Engineering, Indian Institute of Technology, Bombay Mumbai - 400076, India
Atul
Sharma
Department of Mechanical Engineering, Indian Institute of Technology, Bombay Mumbai, India
Amit
Agrawal
Department of Mechanical Engineering, Indian Institute of Technology, Bombay, Mumbai, 400076, India
Sandip Kumar
Saha
Department of Mechanical Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai – 400 076. Maharashtra, India
two-phase flow
microchannel
numerical
dynamic
level-set method
Numerical study is performed to investigate the bubble dynamics and heat transfer characteristics during flow boiling in a microchannel considering dynamic contact angle models reported in the literature. A two-dimensional domain is chosen where continuity, momentum, and energy equations are solved in two phases using the finite volume method-based semi-explicit pressure projection method. The unsteady bubble interface and bubble growth are identified by the dual-grid level-set method-based numerical model. The results suggest that the Kalliadasis and Chang model predicts the bubble growth closest to the experimental value and is more accurate compared to the static contact angle model. Furthermore, the effects of wall superheat and system pressure on bubble dynamics and heat transfer are studied. It is found that the system pressure and wall superheat have significant effects on the bubble growth characteristics. The transient Nusselt number shows a decreasing trend with the dynamic contact angle model similar to the static contact angle model.
THERMOPHORESIS AND BROWNIAN MOTION EFFECTS ON MHD MICROPOLAR NANOFLUID FLOW PAST A STRETCHING SURFACE WITH NON-UNIFORM HEAT SOURCE/SINK
55-77
10.1615/ComputThermalScien.2020027016
Kempannagari Anantha
Kumar
Department of Sciences and Humanities, Sri Venkateswara Engineering College, Karakambadi
Road-517507, Tirupati, Andhra Pradesh, India; Department of Mathematics, Sri Venkateswara University, Tirupati-517502, India
Vangala
Sugunamma
Department of Mathematics, Sri Venkateswara University, Tirupati-517502, A.P., India
Naramgari
Sandeep
Department of Mathematics, Central University of Karnataka, Kalaburagi-585367, India
MHD
Joule heating
heat and mass transfer
Brownian motion
stretching sheet
This report presents the combined influence of heat and mass transfer on magnetohydrodynamic stagnation point flow of micropolar nanoliquid over a stretching surface. The fluid flow is assumed to be steady and laminar. The impacts of thermal radiation, first order velocity slip, non-uniform heat source/sink, and chemical reaction are considered. The nanofluid model is considered in this work in view of the response of Brownian motion and thermophoresis. Appropriate similarity transformations are used to transform the governing partial differential equations to dimensionless ordinary differential equations (ODEs), which are highly nonlinear and coupled. A fourth order Runge-Kutta-based shooting method is utilized to solve the nonlinear coupled ODEs. Impacts of various physical parameters on the fields of velocity, micro-rotation, and temperature are denoted through graphs. Computations for friction factor, couple stress, local Nusselt number, and Sherwood number are carried out. Results indicate that an increase in the magnitude of Brownian motion and thermophoresis parameters amplifies the thermal field, whereas the fluid concentration becomes reduced with a boost in Brownian motion parameter.
NUMERICAL SOLUTIONS FOR AXISYMMETRIC NON-NEWTONIAN STAGNATION ENROBING FLOW, HEAT, AND MASS TRANSFER WITH APPLICATION TO CYLINDRICAL PIPE COATING DYNAMICS
79-97
10.1615/ComputThermalScien.2020026228
O. Anwar
Bég
Aeronautical and Mechanical Engineering, University of Salford, Manchester, M54WT, UK
Rama
Bhargava
Mathematics Department, Indian Institute of Technology Roorkee, Uttarakhand 247667, India
Sapna
Sharma
School of Mathematics, Thapar University, Patiala, Punjab 147001, India
T. A.
Bég
Computational Mechanics and Renewable Energy, Dickenson Road, Manchester, M13, UK
MD.
Shamshuddin
Department of Mathematics, Vaagdevi College of Engineering (Autonomous), Warangal, Telangana, India.
Ali
Kadir
Aeronautical and Mechanical Engineering, University of Salford, Manchester, M54WT, UK
micropolar
thermal conductivity
stagnation point
finite-element method
enrobing
Heat and mass transfer in variable thermal conductivity micropolar axisymmetric stagnation enrobing flow on a cylinder is studied. Numerical solutions are obtained with an optimized variational finite-element procedure and also a finite-difference method. Graphical variations of velocity, angular velocity, temperature, and concentration are presented for the effects of Reynolds number, viscosity ratio, curvature parameter, Prandtl number, and Schmidt number. Excellent agreement is obtained for both finite-element method (FEM) and finite-difference method (FDM) computations. Further validation is achieved with a Chebyshev spectral collocation method (SCM). Skin friction is elevated with greater Reynolds number, whereas it is suppressed with increasing micropolar parameter. The heat transfer rate decreases with an increase in the thermal conductivity parameter. Temperature and thermal boundary layer thickness are reduced with increasing thermal conductivity parameter and Reynolds number. A greater Reynolds number accelerates the microrotation values. A higher Schmidt number reduces the mass transfer function (species concentration) values. The mathematical model is relevant to polymeric manufacturing coating (enrobing) flows.