Transition to periodic unsteady and effects of Prandtl and Richardson numbers on the flow across a confined heated trapezoidal prism

Parveez, Malik; Dhiman, Amit; Rasool, Tanveer

doi:10.1007/s40430-014-0258-4

Cited by 6 publications

(5 citation statements)

References 23 publications

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“…The literature review presented here succinctly reveals that some problems [4,6,9,14,15] related to (aiding and/ or cross buoyancy) mixed convection for square and other geometries are reported. However, the problem of aiding buoyancy mixed convection for the converging and diverging type of geometries is not explored.…”

Section: Previous Investigationsmentioning

confidence: 96%

“…On increasing Ri, overall coefficients (drag and lift) were found to decrease in the steady regime for both cylinders. The flow around a confined trapezoidal cylinder was inspected for Pr = 0.71 and Ri = 0-1 in [15]. The critical values of Re (Reynolds number at which transition occurs from steady to periodic) attained were 37, 61 and 92 for the blockages of 12.5, 25 and 50%, respectively.…”

Section: Previous Investigationsmentioning

confidence: 99%

“…In a recent study [14], cross buoyancy effects were reported for both converging and diverging cylinders. However, in another study [15], the blockage effects were carried out for a trapezoidal geometry in the confined framework. The heat transfer enhancement, correlations of wake length and Nusselt number as a function of Ri and Re and comparison of converging and diverging effects of the trapezoidal cylinder under aiding buoyancy are new things which are explored in this study.…”

Section: Previous Investigationsmentioning

confidence: 99%

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Aiding buoyancy driven flow and heat transfer features of converging and diverging trapezoidal cylinders

2018

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Numerical computations have been carried out to explore the influence of mixed convection heat transfer from heated trapezoidal geometries of two different configurations namely converging and diverging cylinders in a vertical domain. The recirculation length of the diverging cylinder is found to be more than that of the converging cylinder for all values of Re (5 to 40) considered in this study and this length decreases after introducing buoyancy effect. Drag coefficients decrease with increase in Re for a fixed Ri. However, drag increases for the increasing values of Ri (values considered up to 1). The drag coefficient is found to be the smaller for diverging cylinder than that of converging one. Local Nusselt number shows significant increase as Re and Ri values increase, which results in enhanced heat transfer. Keeping Ri fixed and increasing the value of Re results in the augmentation of heat transfer and is around 15% at Re = 5 and 23% at Re = 40 for Ri = 0 for a square cylinder with respect to diverging cylinder. Under the influence of aiding buoyancy, the values of average Nusselt number (Nu) for the diverging cylinder are higher compared to that of converging cylinder. A correlation expressing functional relationship of Nu with Re and Ri has also been generated.

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Section: Previous Investigationsmentioning

confidence: 96%

Section: Previous Investigationsmentioning

confidence: 99%

Section: Previous Investigationsmentioning

confidence: 99%

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Aiding buoyancy driven flow and heat transfer features of converging and diverging trapezoidal cylinders

2018

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“…A structured mesh is being used here based on our previous studies. 14–16,19 For selection of grid in case of the tapered body, two nonuniform grids with 147,608 and 162,458 quadrilateral cells with 100 and 125 control volumes (CVs) on the surface of the bluff body were simulated at Re = 50, Ri = 1, and Pr = 0.7. The percentage deviation in total drag coefficient, Nusselt, and Strouhal numbers was found to be about 0.9, 0.4, and 1.8%, respectively.…”

Section: Problem Description and Numerical Detailsmentioning

confidence: 99%

“…They observed that the onset of flow separation is between Re ¼ 4 and 5 for the blockage ratio of 0.125 and between Re ¼ 5 and 6 for the blockage ratios of 0.25 and 0.5. Parveez et al 16 studied the transition to periodic unsteady regime and the effects of Pr (0.71-100) and Ri (0-1) on the flow across a confined (0.125-0.5) heated trapezoidal prism at low Re. The critical value of the Re exists between Re ¼ (36 and 37), (60 and 61), and (91 and 92) for the blockage ratios of 0.125, 0.25, and 0.5, respectively.…”

Section: Introductionmentioning

confidence: 99%

A comparative study on cross-buoyancy mixed convection around expanded and tapered trapezoidal bluff bodies

Verma

Dhiman

2015

Proceedings of the Institution of Mechanical Engineers, Part E:

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Numerical computations have been realized to explore and evaluate the laminar mixed convection heat transfer from a heated trapezoidal bluff body. Two different configurations of the trapezoidal bluff body viz. expanded and tapered considered and a comparison has been made at different operational parameters. The spectrum of physical control parameters considered as Reynolds number (Re) ¼ 10-50, Richardson number (Ri) ¼ 0-1, and Prandtl number (Pr) ¼ 0.7 (air). A finite volume method implemented on the collocated grid arrangement has been employed for numerical computations. Overall drag and lift coefficients are found higher for a tapered body as compared to an expanded body. However, average Nusselt number is greater for the expanded body as compared to the tapered one. With increase in Re at a given Ri, total drag coefficient is found to decrease in steady regime, but it increases in time-periodic regime. On increasing Ri, drag and lift coefficients decrease in the steady regime for both geometries. A correlation expressing the functional relationship of average Nusselt number with Re and Ri for both geometries has been proposed. Critical Re at Ri ¼ 0.5 for the expanded geometry is found to be between Re ¼ 46 and 47, while for the tapered body it exists between Re ¼ 35 and 36. Maximum heat transfer enhancement for the tapered body with respect to the expanded body at Ri ¼ 0, 0.5, and 1 is found to be approximately 26, 24, and 21%, respectively.

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Hydrodynamic and thermal study of a trapezoidal cylinder placed in shear-thinning and shear-thickening non-Newtonian liquid flows

Dhiman

Ghosh

Baranyi

2019

International Journal of Mechanical Sciences

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Transition to periodic unsteady and effects of Prandtl and Richardson numbers on the flow across a confined heated trapezoidal prism

Cited by 6 publications

References 23 publications

Aiding buoyancy driven flow and heat transfer features of converging and diverging trapezoidal cylinders

Aiding buoyancy driven flow and heat transfer features of converging and diverging trapezoidal cylinders

A comparative study on cross-buoyancy mixed convection around expanded and tapered trapezoidal bluff bodies

Hydrodynamic and thermal study of a trapezoidal cylinder placed in shear-thinning and shear-thickening non-Newtonian liquid flows

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