Numerical study of fully developed unsteady flow and heat transfer in asymmetric wavy channels

Ramgadia, Abhishek G.; Saha, A.

doi:10.1016/j.ijheatmasstransfer.2016.05.131

Cited by 32 publications

(5 citation statements)

References 23 publications

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“…Ramgadia et al 11 numerically explored the fully developed fluid flow and heat transfer characteristics in asymmetric wavy walled channels; they used the finite‐volume technique to solve the governing equations. It was found that most asymmetric geometries result in better heat transfer as compared with symmetrical shapes, but with a higher friction penalty.…”

Section: Introductionmentioning

confidence: 99%

Computational analysis of the thermal performance of rarefied air flow in V‐shaped microchannels

et al. 2021

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In this study, a computational fluid analysis of a slip flow developing thermally and hydrodynamically in a triangular microchannel has been considered. The wall of the channel is preserved at a fixed temperature. Temperature jump and velocity slip boundary conditions are imposed on the surfaces. The microchannel is constructed from seven triangular‐shaped channels and the angle of the microchannel (θ) is varied from 0° to 40°. Simulations are carried out for 1 ≤ italicRe ≤ 8 , 0 ≤ italicKn ≤ 0.1, and the air is used as a working fluid with variable physical properties. The simulation results show that the triangular microchannel can improve heat transfer as compared with plain microchannels. An optimal θ of 20° is found to provide the best heat transfer at moderate frictional losses. Finally, correlations for the average Nusselt number and the average friction coefficient among all parameters are proposed as follows: trueNu ̅ = 4.015 Re 0.0255 Kn − 0.1 ( normalsin θ ) − 0.0479, trueC f ̅ = 3.71 Re − 1.218 italicKn − 0.296 ( normalsin θ ) − 0.495.

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Section: Introductionmentioning

confidence: 99%

Computational analysis of the thermal performance of rarefied air flow in V‐shaped microchannels

et al. 2021

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“…Their results showed that the channel with the sinusoidal-wall geometry produces the highest heat transfer coefficient as compared to the arc-shaped and the triangle-shaped geometries. In a recent study of the same authors (Ramgadia and Saha) [18], a numerical study of a fully developed flow and heat transfer performance was carried out through asymmetric wavy-walled geometry. Three different wavy channels geometries were created through three different values of phase shift angles between the upper and lower wavy walls of the channel.…”

Section: -Introductionmentioning

confidence: 99%

Effect of rotation on forced convection in wavy wall channels

Al-Zurfi

Alhusseny

Nasser

2020

International Journal of Heat and Mass Transfer

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In this paper, flow field and heat transfer performance in stationary and rotating wavy channels with different shapes were numerically investigated. Three different geometries were generated through three different values of phase-shift angles of = 0, 90 and 180 degrees between ∅ the two opposite wavy walls. A cell-centred finite-volume technique was employed to solve the three-dimensional governing equations based on the SIMPLE algorithm technique. Besides, the Menter k-SST turbulence model was used to simulate the turbulent flow in the current study. The wavelength and wave amplitude of the channel examined were L w =20 mm and a=2 mm, respectively. Numerical simulations were carried out over a range of design and operating conditions including the phase-shift angle of = 0-180 degrees, Reynolds number of Re=1,000-∅ 10,000, and rotating speed of 0-1000 rpm. The results showed that the surface-averaged Ω = Nusselt number increases as Re increases for all shapes of the wavy channel, however, at the expense of the raised pressure losses. Also, the wavy channel with a phase-shift of = 0 deg ∅ showed the highest enhancement in the performance of heat transfer followed by that of 90 ∅ = and 180 deg, respectively. The rotation had a strong impact on the flow field and heat transfer performance. With the increase of rotating speed, lower wall heat transfer coefficient significantly increased, while the upper wall heat transfer coefficient exhibited a slight increase, indicating that those three different geometries of the wavy channels had a good versatility at various values of rotating speeds. The numerical results were compared with those available in the literature, and the results were in a good agreement.

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“…It was noted that the heat transfer improvement at steady flow regime cannot outweigh the high frictional losses, leading to the worse overall thermal performance in comparison with a straight channel. Ramgadia et al numerically studied the fully developed flow and heat transfer in symmetric and asymmetric wavy channels with various phase shifts between wavy walls. It was observed that the most asymmetric wavy channel with constant channel width shows the highest Nusselt number but accompanied by the highest pressure drop penalty.…”

Section: Introductionmentioning

confidence: 99%

Effects of wave number and average radius on flow and heat transfer in a curve‐wave channel

Zhang

Zhao

et al. 2019

Int J Energy Res

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The demand for high cooling capacity heatsinks has been increasingly promoted due to the fast elevated heat generation of modern electronic devices. Highperformance microscale heat exchangers are often accompanied by considerable pressure drop penalty that limits their applications. In order to avoid large pressure drop while maintaining high heat transfer rate, a macroscale curved channel was proposed with applying the periodical wave structure on the channel sidewalls. A three-dimensional conjugated numerical model was established, and the effects of wave number and average radius on the hydrothermal performance were investigated. It was found that the heat transfer performance in the smoothcurve channel is significantly improved due to the wavy sidewalls with a moderate pressure drop penalty. The heat transfer enhancement is more noticeable in the channels with more wave units and smaller average channel radius. Furthermore, it was noted that the periodical thermal entrance effect exists on the inner and the outer convective surfaces of curve-wave channels, which can be attributed to the variations of the secondary flow with the wave direction along the channels.

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Numerical study of fully developed unsteady flow and heat transfer in asymmetric wavy channels

Cited by 32 publications

References 23 publications

Computational analysis of the thermal performance of rarefied air flow in V‐shaped microchannels

Computational analysis of the thermal performance of rarefied air flow in V‐shaped microchannels

Effect of rotation on forced convection in wavy wall channels

Effects of wave number and average radius on flow and heat transfer in a curve‐wave channel

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