Begell House Inc.
Computational Thermal Sciences: An International Journal
CTS
1940-2503
11
6
2019
COMBINED CONVECTION AND RADIATION HEAT TRANSFER IN NON-GRAY PARTICIPATING MEDIA IN A DIFFERENTIALLY HEATED SQUARE CAVITY
489-507
10.1615/ComputThermalScien.2019026257
Shashikant
Cholake
Department of Mechanical Engineering
Indian Institute of Technology, Madras
Chennai, India 600036
S. P.
Venkateshan
Department of Mechanical Engineering, Indian Institute of Information Technology, Design
and Manufacturing, Kancheepuram-600127, India
Thirumalachari
Sundararajan
Thermodynamics and Combustion Engineering
Laboratory Department of Mechanical Engineering
Indian Institute of Technology Madras, Chennai – 600036, India
participating media
non-gray-radiation
natural convection
Natural convection and radiation in a non-gray participating gas mixture in a differentially heated square enclosure is studied numerically. The commercial package ANSYS Fluent 14.5 is used to solve the equations governing flow and energy by the finite volume method. The volumetric radiation source term in the energy equation is governed by the radiative transfer equation (RTE) and it is solved using the discrete ordinates method (DOM). The non-gray behavior of the gas mixture is modeled by the spectral line weighted sum of gray gases (SLW) approach. For an emitting and absorbing medium, the spectral absorption coefficient is modeled alternatively as a gray-SLW temperature dependent quantity, evaluated using the SLW model. User defined functions have been developed to incorporate the radiation source term in the heat transfer equation, while solving the governing equations using Fluent software. The effect of gas mixture mole fraction variation (CO2, H2O, and N2), wall emissivity, Rayleigh number, and convection-radiation interaction are studied. The presence of non-gray gas radiation substantially changes the temperature and flow patterns in the cavity. The results show an augmentation in total Nusselt number and reduction in convective Nusselt number. Comprehensive correlations for total Nusselt number by convection and radiation heat transfer modes are developed which provide insight into the physics associated with the problem.
MODELING TURBULENT COMPRESSIBLE FLOW WITH THERMAL EFFECTS USING AN HP-FINITE-ELEMENT TECHNIQUE
509-522
10.1615/ComputThermalScien.2019028935
Xiuling
Wang
Mechanical and Civil Engineering Department, Purdue University Northwest, Hammond, IN,
46323, USA
David B.
Carrington
Los Alamos National Laboratory
KIVA Combustion Modeling, Theoretical Division
T-3 Fluid Dynamics and Solid Mechanics Group
Los Alamos, NM 87545, USA
Darrell W.
Pepper
NCACM, Department of Mechanical Engineering, University of Nevada Las Vegas, Las Vegas, NV 89154, USA
computational methods
turbulent transport
hp-adaptive
FEM
PCS
k-w turbulent model
compressible flow
An hp-adaptive predictor-corrector split (PCS) finite-element model (FEM) is used to simulate subsonic, transonic turbulent compressible flow. The hp-adaptive algorithm is based on mesh refinement and increasing spectral order to generate accurate simulation results with an exponential converge rate; the PCS projection method employs a fractional step FEM, and it has been shown to produce accurate results over a wide range of flow speeds. A k-ω turbulent closure scheme is used in conjunction with the turbulent form of the Navier-Stokes equations. The hp-FEM PCS system is currently being combined with Los Alamos National Laboratory's spray and chemistry models to advance the accuracy and range of applicability of the KIVA combustion model and software. Test cases results for subsonic flow and transonic flow around NACA0012 airfoil are presented, and good agreement with experimental data is observed. Simulations are conducted for full-scale and microscale airfoils under different thermal effects, and the aerodynamics performance under different conditions are compared.
THERMAL DIFFUSION AND VISCOUS DISSIPATION EFFECTS ON MAGNETOHYDRODYNAMIC HEAT AND MASS FILLED WITH TiO2 AND Al2O3 WATER BASED NANOFLUIDS
523-539
10.1615/ComputThermalScien.2020020011
Kotha
Gangadhar
Department of Mathematics, Acharya Nagarjuna University Ongole Campus, Ongole, A.P., India
N. S. L. V.
Narasimharao
Department of Mathematics, Acharya Nagarjuna University, Ongole, India
B.
Satyanarayana
Department of Mathematics, Acharya Nagarjuna University, Nagajunanagar, India
semi-infinite vertical plate
thermal dispersion
MHD
heat and mass transfer
In the present study, an analytical solution has been carried out to discuss the unsteady free convective flow of heat and mass transfer past a semi-infinite flat plate in the presence of thermal diffusion and viscous dissipation. Two types of nanofluids, namely, TiO2 and Al2O3 water-based nanofluids, have been considered for the present investigation. The plate is moved with a constant velocity U0, temperature, and concentration that are assumed to be fluctuating with time harmonically from a constant mean at the plate. The layer equations are assumed to be of oscillatory type and solved by using the small perturbation technique. The results are presented graphically and discussed for various resulting parameters. Thermal diffusion effect significantly increases the bounded layer thickness.
COMPUTATION OF TRANSIENT RADIATIVE REACTIVE THERMOSOLUTAL MAGNETOHYDRODYNAMIC CONVECTION IN INCLINED MHD HALL GENERATOR FLOW WITH DISSIPATION AND CROSS DIFFUSION
541-563
10.1615/ComputThermalScien.2019026405
Siva Reddy
Sheri
Department of Mathematics, GITAM University, Hyderabad Campus, Telangana, India
O. Anwar
Bég
Aeronautical and Mechanical Engineering, University of Salford, Manchester, M54WT, UK
Prasanthi
Modugula
Department of Mathematics, GITAM University, Hyderabad Campus, Telangana, India
Ali
Kadir
Department of Aeronautical and Mechanical Engineering, Salford University, Manchester, UK
MHD Hall energy generators
corrosive chemical reaction
viscous dissipation
Hall current
thermosolutal buoyancy
inclination
porous media
heat transfer
cross diffusion
MATLAB-FEM
MS-DTM
The present article investigates the collective influence of chemical reaction, viscous dissipation, and Hall current magnetic effects on time-dependent radiative magnetohydrodynamic flow, heat, and mass transfer from an inclined wall embedded in a homogeneous, isotropic high-permeability porous medium. The model developed is relevant to near-wall magnetohydrodynamic energy generator transport phenomena in which chemical corrosion effects may arise during operations. The governing nonlinear partial differential equations for mass, momentum, energy, and species conservation are transformed into a system of coupled nonlinear dimensionless partial differential equations with appropriate similarity variables. The normalized conservation equations are then solved with a robust finite-element method software (MATLAB-FEM) subject to corresponding initial and boundary conditions. Important dimensionless parameters emerging are Eckert number, thermal Grashof number, solutal Grashof number, magnetic body force parameter, Hall parameter, permeability parameter, Dufour number, Soret number, time, radiation-conduction parameter, chemical reaction parameter, heat absorption parameter, Prandtl number, Schmidt number, and wall angle. Extensive discussion of the finite-element formulation, convergence, and validation is provided Skin friction, Nusselt number, and Sherwood number distributions are also provided for selected parameter variation. Validation of solutions with published literature is also included for several special cases, namely nonreactive, nondissipative flow in the absence of heat generation or absorption. Further validation is included using a multistep differential transform method (MS-DTM). The present simulations provide an interesting insight into complex fluid/thermal/species diffusion characteristics in the boundary layer region of relevance to working magnetohydrodynamic (MHD) generator systems.
FLUID FLOW CHARACTERISTICS IN DOUBLE-SIDED LID-DRIVEN MICROCAVITY USING LATTICE BOLTZMANN METHOD
565-577
10.1615/ComputThermalScien.2019028960
Isac
Rajan
Department of Mechanical Engineering, National Institute of Technology Karnataka, Surathkal,
Mangalore 575025, India
D. Arumuga
Perumal
Department of Mechanical Engineering
National Institute of Technology Karnataka, Surathkal
Mangalore, 575025
India
Ajay Kumar
Yadav
Department of Mechanical Engineering, National Institute of Technology Karnataka, Surathkal,
Mangalore 575025, India
micro lid-driven cavity
parallel motion
antiparallel motion
Knudsen number
tangential accommodation momentum coefficient
In this study, we analyze the fluid flow characteristic of rarefied gas flows in double-sided lid-driven microcavity subjected to various combinations of boundary conditions that simulate the slip at the walls using lattice Boltzmann method (LBM) constituting a single relaxation time (SRT) model. The fluid motion inside a closed square container with two rigid walls and two moving walls constitutes an exemplar for internal vortex flows. First, a complicated geometry, namely, the single-sided lid-driven microcavity is studied using the LBM-SRT model. Next, this code is extended to simulate flows in a double-sided microcavity flow. Numerical computation of fluid flow incorporating various slip boundary conditions as bounce-back and specular boundary condition (BSBC) for different values of tangential accommodation momentum coefficient (TMAC) has been investigated. Various values of Knudsen number in the slip and transition regime (Kn = 0.01, 0.05, 0.10, 0.135, and 0.15) along with different aspect ratios of 0.33, 0.50, 1.0, 2.0, and 3.0 have been considered in this study. The streamline patterns and velocity profiles were obtained for different Knudsen numbers. The formation and movement of primary vortices have been well captured with the variation of Knudsen numbers for different aspect ratios of microcavity.