International Journal of Thermofluid Science and Technology

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Open AccessArticle

Flow and heat transfer of Oldroyd-B nanofluid with relaxation-retardation viscous dissipation and hyperbolic boundary conditions

by S Mishra, A Misra and M K Nayak

Int. J. Thermofluid Sci. Technol. 2020, 7(1), 070104; https://doi.org/10.36963/IJTST.20070104 - 29 Apr 2020

Cited by 5 | Viewed by 39

Abstract

In the present research article, modeling and computations are presented to introduce the novel concept of relaxation-retardation viscous dissipation and hyperbolic time variation boundary conditions on the magnetohydrodynamic transient flow of Oldroyd-B nanofluid past a vertical stretched plate for the first time. In the present work, firstly we implement Buongiorno’s model to illustrate Brownian motion and thermophoretic diffusion which take vital role in heat and mass transportation process. Nonlinear non-dimensional governing equations are solved by fourth order Runge-Kutta method along with shooting technique. We investigate the behavior of influential variables on the velocity, thermal and solutal fields through graphical illustrations. Our results indicate that relaxation and retardation Deborah numbers exhibit completely reverse trend in the flow field. Especially, augmented relaxationretardation viscous dissipation invigorates the temperature gradient. The results of the current theoretical study may be instrumental for worthful practical applications Full article

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Open AccessArticle

Perturbation analysis of thermophoresis, hall current and heat source on flow dissipative aligned convective flow about an inclined plate

by G. Dharmaiah, O.D. Makinde and K.S. Balamurugan

Int. J. Thermofluid Sci. Technol. 2020, 7(1), 070103; https://doi.org/10.36963/IJTST.20070103 - 15 Feb 2020

Cited by 10 | Viewed by 40

Abstract

This present examination researches the impacts of thermophoresis, heat source and Hall current on dissipative adjusted MHD joint convection stream about an inclined plate inserted in a permeable medium. Utilizing dimensionless variables, the system of partial differential equations is changed into dimensionless equations. By making use of perturbation technique, estimated solutions for velocity, temperature, concentration profiles, skin friction, rate of heat transfer and rate of mass transfer have been determined. The attained results are explained with an assistance of diagrams to examine the impact of distinct parameters such as Magnetic parameter (M), Aligned magnetic parameter (ξ), Schmidt number (Sc), Eckert number (Ec), inclined angle (α), Prandtl number (Pr), heat generation parameter (Q), and chemical reaction (Kr), assuming two cases viz. Case I: Gr < 0, Gm < 0 (flow on heated plate); Case II: when Gr > 0, Gm > 0(flow on cooled plate). Additionally, the impacts of the appropriate parameters on the skin-friction coefficient and rates of heat and mass transfer are numerically furnished in tabular form. Skin friction coefficients are firmly diminished as magnetic field rises. Sherwood and Nusselt numbers boost up as enhance in chemical reaction. Full article

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Open AccessArticle

Thermal Energy Storage Through Melting of a Commercial Phase Change Material in an Annulus with Radially Divergent Longitudinal Fins

by Tonny Tabassum, Mainul Hasan and Latifa Begum

Int. J. Thermofluid Sci. Technol. 2020, 7(1), 070102; https://doi.org/10.36963/IJTST.20070102 - 10 Jan 2020

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Abstract

This study reports on the unsteady two-dimensional numerical investigations of melting of a paraffin wax (phase change material, PCM) which melts over a temperature range of 8.7oC. The PCM is placed inside a circular concentric horizontal-finned annulus for the storage of thermal energy. The inner tube is fitted with three radially diverging longitudinal fins strategically placed near the bottom part of the annulus to accelerate the melting process there. The developed CFD code used in Tabassum et al., 2018 is extended to incorporate the presence of fins. The numerical results show that the average Nusselt number over the inner tube surface, the total melt fraction, the total stored energy all increased at every time instant in the finned annulus compared to the annulus without fins. This is due to the fact that in the finned annulus, the fins at the lower part of the annulus promotes buoyancy-driven convection as opposed to the slow conduction melting that prevails at the bottom part of the plain annulus. Fins with two different heights have been considered. It is found that by extending the height of the fin to 50% of the annular gap about 33.05% more energy could be stored compared to the bare annulus at the melting time of 82.37 min for the identical operating conditions. The effects of fins with different heights on the temperature and streamfunction distributions are found to be different. The present study can provide some useful guidelines for achieving a better thermal energy storage system. Full article

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Heat Transfer Analysis on Peristaltic Transport of a Jeffery Fluid in an Inclined Elastic Tube with Porous Walls

by G. Manjunatha, C. Rajashekhar, Hanumesh Vaidya, K. V. Prasad, Saraswati and B. B. Divya

Int. J. Thermofluid Sci. Technol. 2020, 7(1), 070101; https://doi.org/10.36963/IJTST.20070101 - 10 Jan 2020

Cited by 6 | Viewed by 41

Abstract

This article analyses the effects of heat transfer and thermal conductivity on the peristaltic transport of Jeffery fluid through an inclined elastic tube with porous walls. The velocity slip and convective boundary conditions are taken into account. The modeled governing equations are solved analytically by considering the long wavelength and small Reynolds number approximations. The closed-form solutions are obtained for velocity, flow rate, and the theoretical determination of flow rate is calculated with the help of equilibrium condition given by Rubinow and Keller. A parametric analysis has been presented to study the effects of Jeffery parameter, thermal conductivity, Darcy number, the angle of inclination, velocity slip, Biot number, amplitude ratio, Prandtl number, and Eckert number on velocity, flow rate, and temperature are scrutinized. The streamlines show that the bolus moves with the same speed as that of the wave and further the study reveals that an increase in the Biot number reduces the magnitude of the temperature. Full article

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Int. J. Thermofluid Sci. Technol., Volume 7, Issue 1 (01 2020) – 4 articles

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