Faculty Publications
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Item Lattice Boltzmann computation of two dimensional differentailly heated cavity of incompressible fluid with different aspect ratios(Institute of Electrical and Electronics Engineers Inc., 2017) Karki, P.; Yadav, A.K.; Arumuga Perumal, D.A.Lattice Boltzmann Method (LBM) is a novel computational technique to solve fluid flow problem in bounded domain. Continuum based methods are being widely used to solve the natural convection problem, whereas in the last two decades, mesoscopic approach has gained popularity to solve heat transfer and fluid flow problems. In natural convection cavity, density difference caused by heating and cooling of fluid at different locations gives rise to buoyancy force which in turn drives the fluid flow. The right side and left side wall of the cavity is made hot and cold respectively whereas top and bottom walls are made adiabatic. In the present work, natural convection problem of differently heated cavity with constant Prandtl number (Pr = 0.71) and varying Rayleigh number (Ra =103-106) is solved employing LBM to study the effect of various aspect ratios (H/L) on both Nusselt number and streamlines. Results are plotted in the form of streamlines and isotherms for different Rayleigh numbers at different aspect ratios. Nusselt numbers are obtained at the hot wall and cold wall to study the rate of heat transfer. Obtained results are compared with the existing results. It is found that with increase of Rayleigh number, there is increase in the Nusselt number. The increment in aspect ratio leads to the significant decrement in the Nusselt number and vice versa. © 2017 IEEE.Item Computation of fluid flow in double sided cross-shaped lid-driven cavities using Lattice Boltzmann method(Elsevier Ltd, 2018) Bhopalam, S.B.; Arumuga Perumal, D.A.; Yadav, A.K.This work implements Lattice Boltzmann method to compute flows in double-sided cross-shaped lid-driven cavities. Firstly, a complicated geometry which is a symmetrized version of the staggered lid-driven cavity namely, the double-sided cross-shaped lid-driven cavity with antiparallel uniform wall motion is studied employing Single as well as Two Relaxation time models. The streamline patterns and vorticity contours obtained for low to moderate Reynolds numbers (150–1000) are compared with published results and found to be in good accordance. Next, this code is extended to simulate flows in a double-sided cross-shaped lid-driven cavity with parallel uniform wall motion. The effect of three dimensionality is also studied for low Reynolds numbers. Lattice Boltzmann method is then used to investigate the oscillating double-sided cross-shaped lid-driven cavity with antiparallel and parallel wall motions. The movement and formation of primary and secondary vortices have been well captured with the variation of Reynolds numbers and oscillating frequencies for uniform and oscillating wall motions. Reasonable agreements with the established results have been observed for the double-sided cross-shaped cavity with uniform wall motions, while new results have been obtained in the case of oscillating wall motions. © 2018 Elsevier Masson SASItem Study of adiabatic obstacles on natural convection in a square cavity using lattice boltzmann method(American Society of Mechanical Engineers (ASME) infocentral@asme.org, 2019) Karki, P.; Yadav, A.K.; Arumuga Perumal, D.A.This study involves the effect of adiabatic obstacles on twodimensional natural convection in a square enclosure using lattice Boltzmann method (LBM). The enclosure embodies squareshaped adiabatic obstacles with one, two, and four in number. The single obstacle in cavity is centrally placed, whereas for other two configurations, a different arrangement has been made such that the core fluid zone is not hampered. The four boundaries of the cavity considered here consist of two adiabatic horizontal walls and two differentially heated vertical walls. The current study covers the range of Rayleigh number (10 3 ? Ra ? 10 6 ) and a fixed Prandtl number of 0.71 for all cases. The effect of size of obstacle is studied in detail for single obstacle. It is found that the average heat transfer along the hot wall increases with the increase in size of obstacle until it reaches an optimum value and then with further increase in size, the heat transfer rate deteriorates. Study is carried out to delineate the comparison between the presences of obstacle in and out of the conduction dominant zone in the cavity. The number of obstacles (two and four) outside of this core zone shows that heat transfer decreases despite the obstacle being adiabatic in nature. © 2019 by ASME.Item Comparative studies on air, water and nanofluids based Rayleigh–Benard natural convection using lattice Boltzmann method: CFD and exergy analysis(Springer Science and Business Media B.V., 2022) Karki, P.; Arumuga Perumal, D.A.; Yadav, A.K.The present study incorporates laminar natural convection and entropy generation in Rayleigh–Benard (R–B) convection with air, water and alumina–water nanofluid as working fluids. The fluid flow and energy equations are solved using D2Q9 and D2Q5 LBM models, respectively. The effects of Rayleigh numbers (Ra = 5 × 103, 104, 105) and volume fractions (? = 0 to 0.08) of nanoparticles on heat transfer and irreversibility are investigated. Results show that the heat transfer evaluated based on Nusselt number is enhanced due to addition of nanoparticles in the base fluid. The maximum enhancement in Nusselt number is found to be 13.93% at Ra = 105 with 8% of nanoparticle in base fluid. The various irreversibilities considered in this study are thermal, fluid flow and total irreversibility, where fluid flow and total irreversibilities in the study depend on irreversibility ratio. The irreversibility ratios taken into account are 10–2, 10–3, 10–4 and 10–5. One facet of study shows the deviation in onset of critical Rayleigh number for air is 1.58%. The other facet indicates dimensionless heat transfer, fluid flow and total irreversibility decrease with the increase in volume fraction of nanoparticles in the base fluid. The analyzed results of irreversibilities are presented in normalized form. In addition, dimensionless entropy generation maps and Bejan number contours are also plotted. © 2021, Akadémiai Kiadó, Budapest, Hungary.Item Three-dimensional simulations of fluid flows in oscillating lid-driven cavities using lattice Boltzmann method(Institute of Physics, 2023) Bhopalam, S.R.; Arumuga Perumal, D.A.; Yadav, A.K.We utilize the lattice Boltzmann method to conduct three-dimensional simulations of incompressible flows in oscillating cubic lid-driven cavities. Our investigation focuses on examining the impact of Reynolds number and oscillating frequency on the flow field. Notably, we observe that the flow field can be adequately approximated as two-dimensional within the low and intermediate Reynolds number range, but this approximation is no longer valid for high Reynolds numbers. Additionally, we find that high Reynolds numbers correspond to transient flow fields, while low and moderate Reynolds numbers exhibit quasi-steady periodic flow fields. Our study holds significant relevance for industrial processing applications, where the Reynolds numbers and oscillating frequencies can be optimized to achieve a desired flow field. © 2023 The Japan Society of Fluid Mechanics and IOP Publishing Ltd.