Options
Arvind Pattamatta
Loading...
Preferred name
Arvind Pattamatta
Official Name
Arvind Pattamatta
Alternative Name
Pattamatta, Arvind
Pattamattaa, Arvind
Main Affiliation
Email
Scopus Author ID
Google Scholar ID
15 results
Now showing 1 - 10 of 15
- PublicationEstimation of an appropriate lattice structure for phonon transport using lattice boltzmann method(01-12-2013)
;Chattopadhyay, AnkurHeat transport at nanoscales departs substantially from the well established classical laws governing the physical processes at continuum level. The Fourier Law of heat conduction cannot be applied at sub-continuum level due to its inability in modeling non-equilibrium energy transport. Therefore one must resort to a rigorous solution to the Boltzmann Transport Equation (BTE) in the realm of nanoscale transport regime. Some recent studies show that a relatively inexpensive and accurate way to predict the behavior of sub continuum energy transport in solids is via the discrete representation of the BTE referred to as the Lattice Boltzmann method (LBM). Although quite a few numerical simulations involving LBM have been exercised in the literature, there has been no clear demonstration of the accuracy of LBM over BTE; also there exists an ambiguity over employing the right lattice configurations describing phonon transport. In the present study, the Lattice Boltzmann Method has been implemented to study phonon transport in miniaturized devices. The initial part of the study focuses upon a detailed comparison of the LBM model with that of BTE for one dimensional heat transfer involving multiple length and time scales. The second objective of the present investigation is to evaluate different lattice structures such as D1Q2, D1Q3, D2Q5, D2Q8, D2Q9 etc. for 1-D and 2-D heat conduction. In order to reduce the modeling complexity, gray model assumption based on Debye approximation is adopted throughout the analysis. Results unveil that the accuracy of solution increases as the number of lattice directions taken into account are incremented from D2Q5 to D2Q9. A substantial increase in solution time with finer directional resolutions necessitates an optimum lattice. A novel lattice dimension 'Mod D2Q5' has been suggested and its performance is also compared with its compatriots. It is also demonstrated that the inclusion of the center point within a particular lattice structure can play a significant role in the prediction of thermal conductivity in the continuum level. However, as the size of the device comes down to allow high Knudsen numbers, in the limiting case of ballistic phonon transport, the choice of lattice seems to have negligible effect on thermal conductivity Copyright © 2013 by ASME. - PublicationTransient heat transfer measurements for planar and circular wall jet using liquid crystal thermography(01-01-2016)
;Godi, Sangamesh C.; The objective of this study is to compare the fluid flow and the heat transfer characteristics between a 2-D planar and a 3-D circular wall jet along the stream wise direction. The experiments are performed at a Reynolds number of 5540 for nondimensional streamwise distance ranging from 0 to 40. The hot wire anemometer is used to quantify the velocity distribution on the jet spread and the local maximum velocity decay along the stream wise direction. Liquid Crystal Thermography (LCT) technique is used to map the surface temperature and the semi-infinite approximation methodology is used for extracting the heat transfer coefficient. From the results it is observed that, the 2-D planar wall jet shows lesser distribution of RMS values in the near field and better heat transfer performance than that of the 3-D circular wall jet. - PublicationExperimental investigation on convective heat transfer enhancement of laminar slot jet impingement in the presence of porous medium(01-01-2016)
;Chinige, Sampath KumarAn experimental study using Liquid crystal thermography technique is conducted to study the convective heat transfer enhancement in jet impingement cooling in the presence of porous media. Aluminium porous sample of 10 PPI with permeability 2.48e-7 and porosity 0.95 is used in the present study. Results are presented for two different Reynolds number 400 and 700 with four different configurations of jet impingement (1) without porous foams (2) over porous heat sink (3) with porous obstacle case (4) through porous passage. Jet impingement with porous heat sink showed a deterioration in average Nusselt number by 10.5% and 18.1% for Reynolds number of 400 and 700 respectively when compared with jet impingement without porous heat sink configuration. The results show that for Reynolds number 400, jet impingement through porous passage augments average Nusselt number by 30.73% whereas obstacle configuration enhances the heat transfer by 25.6% over jet impingement without porous medium. Similarly for Reynolds number 700, the porous passage configuration shows average Nusselt number enhancement by 71.09% and porous obstacle by 33.4 % over jet impingement in the absence of porous media respectively. - PublicationHeat transfer characteristics of a train of droplets impinging over a hot surface: From film evaporation to leidenfrost point(01-01-2019)
;Guggilla, Ganesh; Narayanaswamy, RameshDue to the advancements in computing services such as machine learning and artificial intelligence, high-performance computing systems are needed. Consequently, the increase in electron chip density results in high heat fluxes and required sufficient thermal management to maintain the servers. In recent times, the liquid cooling techniques become prominent over air cooling as it has significant advantages. Spray cooling is one such efficient cooling process which can be implemented in electronics cooling. To enhance the knowledge of the process, detailed studies of fundamental mechanisms involved in spray cooling such as single droplet and multiple droplet interactions are required. The present work focuses on the study of a train of droplets impinging over a heated surface using FC-72 liquid. The surface temperature is chosen as a parameter, and the Dynamic Leidenfrost point (DLP) for the present impact conditions is identified. Spread hydrodynamics and heat transfer characteristics of these consecutively impinging droplets till the Leidenfrost temperature, are studied and compared. - PublicationParametric design and optimization for impingement jet heat transfer over dimpled topologies(01-12-2012)
;Negi, Deepchand SinghA large number of experimental and theoretical studies investigating heat transfer of impinging jet and jet arrays exist in the literature. However, there are only a few experimental and numerical studies that consider the heat transfer performance of the impinging jet and jet array over complex impinging surface topologies. In spite of these studies, several other factors concerning the dimpled target plate configuration such as dimple height, diameter, pitch spacing between dimples, and their effects on the heat transfer coefficient have not yet been well apprehended. The purpose of the present study is to address some of these aspects through a detailed computational investigation of 3D impinging jet interaction on dimpled target plates. The initial section of the study is focused on the evaluation of different turbulence models in capturing the complex flow features associated with dimpled topology. These models are validated for Nusselt number against previous experimental data in literature. This is followed by a parametric study in which geometric parameters of the dimpled target plate such as dimple diameter, pitch spacing between dimples and dimple height are varied to understand their role on heat transfer enhancement. The final section of the study deals with the optimization of the above geometric parameters based on three factorial design of parametric space. Results from these designed simulations are used to construct a surrogate model based on response surface analysis and the optimized configuration is determined. The objective functions for optimization include maximizing the average Nusselt number, Nuavg, and minimizing the deviation of maximum Nusselt number, Numax-sd. With respect to the reference configuration there is 12% and 8.58 % increase in the average Nusselt number values for the optimized case corresponding to Reynolds number of 3000 and 8200 respectively. Enhancement in terms of Nusselt number is observed with the dimpled target plate over corresponding non dimpled target plates. Copyright © 2012 by ASME. - PublicationAn Experimental Study on Buoyancy Induced Convective Heat Transfer in a Square Cavity using Multi-Walled Carbon Nanotube (MWCNT)/Water Nanofluid(21-10-2016)
;Joshi, PranitIn recent times, convective heat transfer using nanofluid has been a active field of study. However experimental studies pertaining to buoyancy induced convective heat transfer using various nanofluid is relatively scarce. In present study, a square enclosure of dimensions (40 x 40 x 200) mm is used as test section. Initially, Al2 O3 /Water nanofluid with volume fractions 0.3%, 1% and 2% and Rayleigh numbers ranging from 7 x 105 to 1 x 107 are studied. These results are then compared with Ho's[1] experimental data. Nusselt number is calculated based on the thermo-physical properties that are measured in-house for the given conditions. Further, MWCNT/Water nanofluid with volume fractions 0.1%, 0.3% and 0.5% is formulated and are studied for various Rayleigh numbers. Comparison of Al2O3 /Water and MWCNT/Water nanofluid have been made for different volume fractions and for various range of Rayleigh numbers. It is observed that MWCNT/Water nanofluid when compared with Al2 O3 /Water nanofluid yields higher values of the Nusselt number for a given volume fractions. All the existing experimental studies using particle based nanofluid concluded a deterioration in natural convective heat transfer. This study for the first time demonstrates an enhancement in natural convection using MWCNT/Water nanofluid. Such enhancement cannot be simply explained based only on the relative changes in the thermophysical properties. Other factors such as percolation network in MWCNT/Water nanofluid which increases the heat transfer pathway between two walls and the role of slip mechanisms might be the possible reasons for the enhancement. - PublicationEffect of external magnetic field on natural convection in a cubical cavity filled with nano particle suspension.(01-01-2018)
;Dixit, Desh DeepakThis paper reports experimental investigation of Natural Convection of non-magnetic electrically conducting nano-suspension Multi Wall Carbon Nano Tube (MWCNT) and electrically non-conducting Silica nano-particle suspension, in presence of magnetic field in a differentially heated cubicle cavity with two opposite vertical sides at different constant temperature.The main aim of this experimental investigation is to study the effect of Lorentz force on the heat transfer characteristics of nano-particle suspension, which arises due to motion of nano-particles in applied magnetic field. A comparison between two different particles with different electrical properties is done to establish the effect of Lorentz force on the nano-particles and the effect on heat transfer because of interaction between nano-particles and magnetic field. Experiments are done in a cubicle cavity of 25mm side whose one vertical face is maintained at higher temperature by an electrical heater and other opposite vertical face is maintained at lower temperature using cold bath. The results are compared for 2.5 × 106 to 1 × 107 Rayleigh number range, and different magnetic field strength from 0.00 Tesla to 0.30 Tesla in two different perpendicular directions, to study the effect of strength and direction respectively. A suppression in Nusselt number is observed with increase in magnetic field strength, the suppression is more when the magnetic field lines are perpendicular to the convective flow in MWCNT nano-particle suspension. In presence of magnetic field no suppression is observed in case of silica nano-particle suspension. - PublicationEffect Of Subcooling On Pool Boiling Heat Transfer Over Minichannel Surfaces(01-01-2021)
;Dhanalakota, Praveen; In the present work, pool boiling experiments are performed on copper minichannel and flat surfaces at atmospheric pressure with water as the working fluid. The pool boiling experiments are conducted for liquid subcooling of 0K (saturated), 10K, and 20K at atmospheric pressure. Minichannel-1 and Minichannel-2 have a square cross-section with side lengths 1 mm and 2 mm, respectively. The thermal performance of the boiling surface is characterized by the critical heat flux and heat transfer coefficient. The critical heat flux (CHF) is increased by 36-45 % for minichannel-2 and 15-17 % for minichannel-1 compared to a flat surface at all subcoolings. CHF can be increased as high as 287.54 W/cm2 by employing minichannel-2 and 20 K subcooling. Minichannel-1 and minichannel-2 enhanced the heat transfer coefficient as high as 25.21% and 68.59 %, respectively, compared to the flat surface. It is observed that the increase in surface area is the dominant factor in the enhancement of pool boiling heat transfer on minichannel surfaces. - PublicationAn optimization study of heat transfer enhancement due to jet impingement over porous heat sinks using Lattice Boltzmann method(01-01-2014)
;Chinige, Sampath Kumar ;Ghanta, NikhileshIn this paper, an optimization study involving five variable parameters which are critical in evaluating the thermal performance of the air jet flow impingement over porous heat sinks in mixed convection regime is presented. The variable parameters include porous block height, channel height, jet width, porosity and Darcy number. The Lattice Boltzmann method for porous media is used as the numerical tool to simulate the objective functions in terms of Nusselt number and pressure drop. Kriging method combined with Genetic algorithm is used to generate the optimal Pareto plot. Three optimal cases from the pareto plot showing maximum, minimum and optimum Nusselt numbers and pressure drop are considered. The optimized results show that the porosity and Darcy number are relatively invariant along the pareto surface. Thus the geometry of the channel and porous block are the most significant parameters governing Nusselt number and pressure drop values. The results from optimization corresponding to the three optimal cases are analyzed in detail. The local variation in Nusselt number for these cases is also plotted to understand the effect of the channel and porous heat sink parameters on heat transfer. - PublicationInfluence of lateral restraint on thermocapillary migration of wetting droplets(01-01-2019)
;Sagar, Kalichetty Srinivasa ;Dwaraknath, K. G.; Sundararajan, T.The present study aims at studying the characteristics of thermocapillary migration with varying levels of lateral restraints. A temperature gradient is created by heating and cooling either side of the substrate. When a droplet is placed near hot side it spreads as thin film and migrates towards the cold side. The advancing end assumes the shape of a parabolic rim while the receding end stays as a thin film. It is observed that the droplet decelerates to attain a steady state velocity and undergoes slight acceleration near the cold end of the substrate. The observed velocity trend follows the temperature gradient on the substrate. The velocity increases with the droplet volume and substrate temperature gradient. The liquid viscosity is observed to have a diminishing effect on migration velocity. The effect of lateral spread confinement is studied by performing experimental trails on substrates with different widths. It is found that reducing the substrate width increases the migration velocity due to increased footprint resulting in larger thermocapillary force. The results observed in the present study highlights the importance of thermocapillary flows in many academic and industrial applications.