Preetom Nag

Followers

Following

Public Views

Interests

Uploads

Papers by Preetom Nag

Non-Newtonian Effect on Mixed Convection Flow Over an Elliptical Cylinder with Uniform Heat Flux

International Journal of Applied and Computational Mathematics, 2022

Magnetic field effects on natural convection and entropy generation of non-Newtonian fluids using multiple-relaxation-time lattice Boltzmann method

International Journal of Modern Physics C, 2020

The magnetic field effect on natural convection flow of power-law (PL) non-Newtonian fluid has be... more The magnetic field effect on natural convection flow of power-law (PL) non-Newtonian fluid has been studied numerically using the multiple-relaxation-time (MRT) lattice Boltzmann method (LBM). A two-dimensional rectangular enclosure with differentially heated at two vertical sides has been considered for the computational domain. Numerical simulations have been conducted for different pertinent parameters such as Hartmann number, [Formula: see text], Rayleigh number, [Formula: see text], PL indices, [Formula: see text]–1.4, Prandtl number, [Formula: see text], to study the flow physics and heat transfer phenomena inside the rectangular enclosure of aspect-ratio [Formula: see text]. Numerical results show that the heat transfer rate, quantified by the average Nusselt number, is attenuated with increasing the magnetic field, i.e. the Hartmann number (Ha). However, the average Nusselt number is increased by increasing the Rayleigh number, [Formula: see text] and decreasing the PL index...

Download

A Graphics Process Unit-Based Multiple-Relaxation-Time Lattice Boltzmann Simulation of Non-Newtonian Fluid Flows in a Backward Facing Step

Computation, 2020

A modified power-law (MPL) viscosity model of non-Newtonian fluid flow has been used for the mult... more A modified power-law (MPL) viscosity model of non-Newtonian fluid flow has been used for the multiple-relaxation-time (MRT) lattice Boltzmann methods (LBM) and then validated with the benchmark problems using the graphics process unit (GPU) parallel computing via Compute Unified Device Architecture (CUDA) C platform. The MPL model for characterizing the non-Newtonian behavior is an empirical correlation that considers the Newtonian behavior of a non-Newtonian fluid at a very low and high shear rate. A new time unit parameter (λ) governing the flow has been identified, and this parameter is the consequence of the induced length scale introduced by the power law. The MPL model is free from any singularities due to the very low or even zero shear-rate. The proposed MPL model was first validated for the benchmark study of the lid-driven cavity and channel flows. The model was then applied for shear-thinning and shear-thickening fluid flows through a backward-facing step with relatively ...

Download

Non-Newtonian shear thinning effect on natural convection flow over an isothermal elliptical cylinder

AIP Conference Proceedings, 2019

In this paper, laminar natural convection flow of Newtonian and non-Newtonian (shear thinning cas... more In this paper, laminar natural convection flow of Newtonian and non-Newtonian (shear thinning case only) fluid surround an isothermal horizontal cylinder of elliptic cross section has been studied numerically. To characterize the non-Newtonian fluid, a modified power-law viscosity model has been employed. The boundary layer equations governing the flow are transformed into a non-dimensional form and the resulting equations are reduced to a convenient form which are solved numerically by an efficient implicit finite difference method. Numerical results are presented for two significant physical quantity such as the local skin friction coefficients and the rate of surface heat transfer (i.e. the local Nusselt number) as a function of the eccentric angle of an elliptical configurations with different aspect ratio and for different orientation such as blunt and slender. The local skin friction is found to be higher for Newtonian fluid than that of the shear thinning fluid. Furthermore, the total heat transfer rate becomes higher for elliptical cylinder with slender orientation than that of the blunt orientation in the fluids of interest.

Download

1P323 Dynamical heterogeneity and dynamics of cage breaking and formation in colloidal fluids(30. Miscellaneous topics,Poster,The 52nd Annual Meeting of the Biophysical Society of Japan(BSJ2014))

Seibutsu Butsuri, 2014

Biomolecular motor such as kinesin converts chemical energy into mechanical work with a high effi... more Biomolecular motor such as kinesin converts chemical energy into mechanical work with a high efficiency and moves along the microtubule (MT). MTs, introducing biotin-streptavidin interaction, were integrated into assembled structures on a kinesin-coated surface and MT assemblies provide specific motion. However, reversible control of the MT association / dissociation was not achieved. Hence, we prepared DNAmodified MT and control the self-organization of MTs by using DNA interaction. DNA-modified MTs can reversibly associate and dissociate depending on the DNA sequence used. It will offer means to control the assembly of MT and thereby may widen the application of biomolecular motor based nanodevice. 1P320 Cell trapping device for observation of connexin function by a single cell device

Download

3P313 Coherent dynamics in colloidal fluids in terms of Lagrangian coherent structures (LCS)(30.Miscellaneous topics,Poster,The 51st Annual Meeting of the Biophysical Society of Japan)

Seibutsu Butsuri, 2013

Download

Local-heterogeneous responses and transient dynamics in colloidal fluids [an abstract of dissertation and a summary of dissertation review]

All living organisms are composed of basic structural, functional, and biological unit such as ce... more All living organisms are composed of basic structural, functional, and biological unit such as cell. In biology, cell movement is one of the basic components to determine the phenotype. The motility of cells is a highly dynamic phenomenon that is essential to a variety of biological processes such as the embryonic development, wound healing, immune response and the cancer metastasis. For example, in wound healing in animals, white blood cells and macrophages move to the wound site to kill the microorganisms that cause infection. In most of the case, cells reach their target by crawling and sometimes they are found to move collectively. This collective motion indeed refers the heterogeneity in space and time of cells’ motility in a living organism. For example, a confluent epithelial cell sheet exhibits a collective migration and subcellular motion but, depending on the presence of their neighbors. Some cells undergo collective migration but the other cells are transiently disordered...

Download

Multiple-relaxation-time lattice Boltzmann simulation of free convection and irreversibility of nanofluid with variable thermophysical properties

Physica Scripta

This numerical study demonstrates heat transfer and irreversibility or entropy generation of non-... more This numerical study demonstrates heat transfer and irreversibility or entropy generation of non-Newtonian power-law Al2O3-H2O (aluminum oxide-water) nanofluids in a square enclosure using multiple-relaxation-time lattice Boltzmann method accelerated by graphics processing unit computing. In this investigation, the effective thermal conductivity and viscosity are variables, and they depend on the fluid temperature and rate of strain, respectively. The enclosure’s left and right walls are uniformly heated with different temperatures, and the upper and lower walls are thermally adiabatic. There is no valid study and results on non-Newtonian fluid using multiple-relaxation-time lattice Boltzmann method for this configuration and hence the novelty of the present results have been ensured. This paper has formulated and appropriately validated the Newtonian and non-Newtonian natural convection problem with the available numerical results. This study includes a set of comprehensive simulat...

18pAC-6 A novel computational procedure for locating Lagrangian Coherent Structures (LCS) from variational LCS theory

Investigation of MHD free convection of power‐law fluids in a sinusoidally heated enclosure using the MRT‐LBM

Unsteady RANS simulation of wind flow around a building shape obstacle

Building Simulation

This work aims to find the origin and connection of the surface, near-wake, and far-wake structur... more This work aims to find the origin and connection of the surface, near-wake, and far-wake structures in the flow encompassing a high-rise building for a high Reynolds number. The origin and interconnection of the stream-wise tip vortices, with the other components of the wake, is analysed in this study for the current scenario. The Unsteady Reynolds Averaged Navier-Stokes equations (URANS) together with the realizable k-ϵ turbulence model have been used in this investigation to study the turbulent wake flow following a ground-surface-attached square shape building. A moderately big obstacle aspect ratio of 4, a Reynolds number of 12,000, and a thin evolving boundary layer thickness have been used in the flow modeling. The designed flow addresses the reversed-flows at the outlet during computation to improve the accuracy of the realizable k-ϵ model. The Reynolds stress components are retrieved using the Boussinesq approach. The wake’s principal compositions, including span-wise-side eddies and area of high stream-wise vorticity in the uppermost portion of the wake, are illustrated by both three-dimensional (3D) representations and planner projections of the mean flow distributions. A braided vortex formation, composed of asymmetric hairpin vortexes, is witnessed in the far-wake area. The association of the near-wake vortex structures with the far-wake and near-wall flow, which is associated with the flow strengths, is also discussed. In this investigation, few areas of large stream-wise vorticity magnitude, like tip vortexes, are correlated to the 3D curving of the fluid motion, and tip vortices did not continuously reach to the free end part of the building. The 3D fluid motion interpretation, which combined several measurements of the flow distribution encompassing the cylinder, shows that the time-averaged near-wake structures are formed of two segments of distinct source and section of dominance. Furthermore, addressing reversed-flow during computation shows notable improvement in the results.

Lattice Boltzmann simulation of natural convection and heat transfer from multiple heated blocks

Heat Transfer

Non-Newtonian effect on heat transfer and entropy generation of natural convection nanofluid flow inside a vertical wavy porous cavity

SN Applied Sciences

A numerical study on heat transfer and entropy generation in natural convection of non-Newtonian ... more A numerical study on heat transfer and entropy generation in natural convection of non-Newtonian nanofluid flow has been explored within a differentially heated two-dimensional wavy porous cavity. In the present study, copper (Cu)–water nanofluid is considered for the investigation where the specific behavior of Cu nanoparticles in water is considered to behave as non-Newtonian based on previously established experimental results. The power-law model and the Brinkman-extended Darcy model has been used to characterize the non-Newtonian porous medium. The governing equations of the flow are solved using the finite volume method with the collocated grid arrangement. Numerical results are presented through streamlines, isotherms, local Nusselt number and entropy generation rate to study the effects of a range of Darcy number (Da), volume fractions (ϕ) of nanofluids, Rayleigh numbers (Ra), and the power-law index (n). Results show that the rate of heat transfer from the wavy wall to the ...

Download

Double-diffusive natural convection of non-Newtonian nanofluid considering thermal dispersion of nanoparticles in a vertical wavy enclosure

AIP Advances

The flow field, thermal field, and solutal field exposed to thermal and solutal buoyancy forces h... more The flow field, thermal field, and solutal field exposed to thermal and solutal buoyancy forces have been investigated in detail within a wavy enclosure filled with copper(Cu)-water nanofluid incorporating the non-Newtonian characteristics predicted by the power-law viscosity model. During the convection process, the random motion of ultrafine Cu-nanoparticles causing an enhanced energy exchange rate is determined using the thermal dispersion model. The governing equations in a dimensionless form are numerically solved utilizing the finite volume method incorporated with the semi-implicit method for pressure linked equations-revised algorithm. The simulations are carried out with different pertinent parameters, such as the Rayleigh number, Lewis number, power-law index, volume fraction, and buoyancy ratio. The effect of the above parameters on the local Nusselt number (Nu) and the local Sherwood number (Sh) is analyzed to understand the heat and mass transfer properties from the heated wavy surface. Results show that the heat transfer rate from the wavy surface declines, but the mass transfer rate gets stronger with growing Lewis number. Both the heat and mass transfer rates become optimum when the nanofluid behaves as a shear thinning fluid. The distribution of Nu and Sh is found to be periodically attenuated from the lower end to the upper end along the hot wavy surface. The distribution of Nu and Sh is observed to be locally maximum at the crest point of the wavy surface. New correlations to predict the average heat and mass transfer rate concerning the studied parameters are proposed with remarkable accuracy.

Download

Magnetic field effects on Natural convection and Entropy Genera-tion of non-Newtonian fluids using Multiple-relaxation-time lattice Boltzmann method

Internatuional Journal of Modern Physics C, 2021

In this paper, the magnetic field effect on natural convection flow of power-law non-Newtonian fl... more In this paper, the magnetic field effect on natural convection flow of power-law non-Newtonian fluid has been studied numerically using the multiple-relaxation-time (MRT) lattice Boltzmann method (LBM). As for the geometry, a two-dimensional rectangular enclosure with differentially heated at two vertical sides has been considered. Numerical simulations have been conducted for different pertinent parameters such as Hartmann number~$(Ha=0 - 20)$, Rayleigh number~$(Ra= 10^4-10^6)$, power-law indices~$(n = 0.6-1.4)$, Prandtl number~$(Pr = 6.2\text{(water)})$ to study the flow physics and heat transfer phenomena inside the rectangular enclosure of aspect-ratio $AR = 2.0$ . Numerical results show that the heat transfer rate, which is quantified by the average Nusselt number, is attenuated with increasing the magnetic field, i.e., the Hartmann number (Ha). However, the average Nusselt number is increased by increasing the Rayleigh number~$(Ra)$ and decreasing the power-law index~$(n)$. Be...

A Graphics Process Unit-Based Multiple-Relaxation-Time Lattice Boltzmann Simulation of Non-Newtonian Fluid Flows in a Backward Facing Step

Computation, 2020

Download

Natural convection flow of nanofluids over horizontal circular cylinder with uniform surface heat flux

Proceedings of the 13th International Conference on Mechanical Engineering (ICME2019)

The behavior of natural convection laminar flow of Nanofluids over a horizontal circular cylinder... more The behavior of natural convection laminar flow of Nanofluids over a horizontal circular cylinder with uniform surface heat flux has been examined. In this study, Copper-Water (Cu-H2O) nanofluid has been chosen with different volume fractions ranging from 0% to 10%. In the present study, the governing boundary layer equations are converted into a dimensionless form, and the resultant non-dimensional set of equations has been transformed into a parabolic system of partial differential equations by applying a specific set of variables. The set of parabolic equations has been numerically solved using an implicit finite difference method. The outcomes of the numerical simulation have been compared and validated with an excellent agreement with the previously published work. The numerical results have been depicted in terms of the velocity and temperature profiles. Finally, the skin friction coefficient (Cf) and the local Nusselt number (Nu) has been outlined to understand the feature of the wall shear stress and the surface heat transfer rate, respectively.

Lattice Boltzmann simulation of MHD non-Newtonian power-law nanofluid in a rectangular enclosure using GPU computing

Proceedings of the 13th International Conference on Mechanical Engineering (ICME2019)

In this paper, a numerical study has been conducted on the heat transfer of non-Newtonian nanoflu... more In this paper, a numerical study has been conducted on the heat transfer of non-Newtonian nanofluid (Copper-Water) in a vertical rectangular cavity in the presence of a horizontal or angular magnetic field. The numerical simulation has been accomplished using the graphics process unit (GPU) accelerated multiple-relaxation-time (MRT) lattice Boltzmann method. A modified power-law model has been employed to characterize the non-Newtonian fluid behavior. The simulation presented in this paper spans a range of power-law index (0.6 ≤ n ≤ 1.0), Hartmann number (0 ≤ Ha ≤ 50) and nanoparticle volume fraction (0 ≤ φ ≤ 0.05). Results indicate that an increment of the power-law index leads to reduce the heat transfer rate from the hot walls. The heat transfer rate also drops when the Hartmann number is incremented. Moreover, augmentation of the volume fraction of nanofluids can enhance the average Nusselt number. Finally, the average Nusselt number increases when the magnetic field is applied at a different angle instead of 0 • .

Non-Newtonian effect on double diffusive natural convection of nanofluid within a square cavity

Proceedings of the 13th International Conference on Mechanical Engineering (ICME2019)

In this work, the non-Newtonian effect on double-diffusive natural convection of nanofluid flow e... more In this work, the non-Newtonian effect on double-diffusive natural convection of nanofluid flow exposed to both temperature and concentration gradient within a square enclosure has been studied numerically. The top and the bottom walls are considered adiabatic and impermeable while the side walls are imposed to constant temperature and concentration. The power-law viscosity model has been employed to characterize the non-Newtonian fluid behavior in the present study. The system of non-dimensional conservation equations for continuity, momentum, energy, and solute concentration are solved using the finite volume method for the SIMPLER algorithm. An in-house FORTRAN code is validated comparing the present results with the benchmark results published before. Results are presented in the form of streamlines, isotherms and iso-concentration for different volume fraction (φ) of the nanofluids and different power-law index (n). The physical quantities like heat and mass transfer rates are presented in terms of the local Nusselt number (Nu) and the local Sherwood number (S h), respectively.

Lattice Boltzmann simulation of natural convection and heat transfer from multiple heated blocks

Heat Transfer

Preetom Nag

Uploads

Papers by Preetom Nag

Log In