Flow past a moderately heated horizontal cylinder at low Reynolds number

A novel and effective hybrid technique, which involves active surface heating strategies in conjunction with the use of passive splitter plates in the wake of the cylinder, is proposed. In this report, we present the results of a numerical investigation on the two-dimensional, laminar mixed convection flow over a circular cylinder with a hot rigid splitter plate attached to it on the wake side. A projection algorithm-based finite volume method is employed to obtain the solution of the coupled, nonlinear governing partial differential equations subjected to Courant–Friedrichs–Lewy conditions. The isothermal heating of the splitter plate under the influence of the gravity field generates an upward buoyancy force in the wake of the cylinder. For different length-to-diameter (L/D) ratios, the effect of heating on aerodynamic, wake, and heat transfer characteristics has been studied for a wide range of parameters; 75 ≤Re≤ 150, 0 ≤Ri≤ 1, and 0.5 ≤L/D≤ 1 at Pr = 0.7. It is observed that the hot splitter plate would bring about conspicuous changes such as asymmetry in the vortex shedding behind the cylinder at low Reynolds numbers. The outcomes demonstrate a notable improvement in convective heat transfer and drag, with gains of up to 7% and 15%, respectively. It is found that the rate of heat transfer and vortex shedding frequency decrease with an increase in L/D ratio. Correlations for the estimation of Strouhal number and Nusselt number have also been proposed which helps provide a more thorough understanding of thermal and aerodynamic features of the hybrid approach.

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Influence of Slip and Orientation on Entropy Generation Due to Natural Convection in a Square Cavity

Murali

Suresh

Arjun

et al. 2022

ASME Journal of Heat and Mass Transfer

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Numerical simulations are performed to deduce the effects of slip wall and orientation on entropy generation due to natural convection in a square cavity for Rayleigh number =100000 . The laterally insulated square cavity, heated at the bottom wall and cooled at the top wall, is subjected to various orientation angles and slip velocities characterised by Knudsen number. The two components of entropy generation i.e. entropy generation due to heat transfer and entropy generation due to fluid friction are separately investigated by varying the orientation from 0 degree to 120 degree and Knudsen number from 0 (no-slip) to 1.5. Evidences indicate that, for most of the cases considered, entropy generation due fluid friction dominates the one due to heat transfer. It is observed that the slip velocity on the isothermal walls has a strong influence on entropy generation due to heat transfer whereas, the variations in entropy generation due to fluid friction are closely connected to the change in the rate of shear strain. Interestingly, the presence of corner vortices and the secondary circulations near to the core of the cavity are also found to affect the variation in entropy generation. The existence of active zones of entropy generation due to heat transfer in the vicinity of isothermal walls and their elongation and migration while changing the orientation is another unique characteristic noticed in the present study. A new parameter called MVR (Maximum Velocity Ratio) is also proposed to highlight the variation in velocity components within the enclosure.

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Flow past a moderately heated horizontal cylinder at low Reynolds number

Cited by 4 publications

References 43 publications

Studies on Flow Past Surface Cooled Circular Cylinder at Low Reynolds Number

Studies on Flow Past Surface Cooled Circular Cylinder at Low Reynolds Number

Flow control using hot splitter plates in the wake of a circular cylinder: A hybrid strategy

Influence of Slip and Orientation on Entropy Generation Due to Natural Convection in a Square Cavity

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