Curvature induced instability characteristics of laminar flow and heat transfer through a bent square channel

Hasan, Mohammad Sanjeed; Mondal, Rabindra Nath; Lorenzini, Giulio

doi:10.1016/j.cjph.2021.10.052

Cited by 5 publications

(1 citation statement)

References 53 publications

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“…Yanase and Nishiyama [17] first inspected the TDF through a CRD and then many more scholars were enticed to explore the nature of UF. Ray et al [18][19] and Saha et al [20] inspected the onset of Dn [22], Hasan et al [23][24][25][26][27] and Chanda et al [28][29][30][31] explored the TDF in CSD and CRD, respectively imposing the rotational force (Coriolis Force) both in the negative and positive directions and demonstrated various types of flow instability. The authors assigned that the flow changes from chaotic to periodic fluctuation, followed by a steady-state solution later.…”

Section: Introductionmentioning

confidence: 99%

A Computational Study on Fluid Flow and Energy Distribution through a Bending Duct with Longitudinal Vortex Generation

Adhikari¹,

Chanda²,

Mondal³

2022

Preprint

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Since studies on fluid flow and energy dissemination through a bending duct (BD) plays prodigious contribution to both engineering and industrial standpoint, scientists have paid considerable attention to disclose new features of fluid flow through a BD. Taking this factor into account, the current work explores a computational approach on flow features and energy distribution through a bending rectangular duct of curvature 0.001 applying a spectral-based numerical scheme over a wide domain of the Dean number 0 < Dn ≤ 3000.The geometry is such that the bottom and outer side walls are thermally heated while the other walls are kept in room temperature. Newton-Raphson iteration method (N-R method) is adopted to inspect the branching structure of steady solutions (SS) which explores that there exist four branches of asymmetric steady solutions comprising 2- to 14-vortex solutions. The axial and secondary velocity distribution for each branch is investigated through different grid points by using different values of Dn. Unsteady flow characteristics are analyzed exquisitely by performing time-advancement of the solutions and flow transition is well determined by analyzing power spectrum (P-S) of the solutions. Axial flow, secondary flow, and temperature profiles have been depicted in accordance with Dn to wander the flow pattern, and it is predicted that the time-dependent flow (TDF) consists of asymmetric 2- to 10-vortex solutions. Finally, convective heat transfer (CHT) is analyzed by acquiring temperature contours for various types of physically realizable solutions. The study also demonstrates that centrifugal force comprehensively influences the fluid nature of the bending channel and CHT is more intensified due to chaotic phenomena of the flow.

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Section: Introductionmentioning

confidence: 99%

A Computational Study on Fluid Flow and Energy Distribution through a Bending Duct with Longitudinal Vortex Generation

Adhikari¹,

Chanda²,

Mondal³

2022

Preprint

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A computational modeling on two-dimensional laminar flow and thermal characteristics through a strongly bent square channel

Adhikari,

Hasan,

Rouf

et al. 2023

AIP Advances

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In order to have a precise knowledge on how pressure gradients and buoyancy force affect fluid flow and energy distribution in a bending channel, it is important to perform a comprehensive study on flow characteristics and heat transfer mechanisms that trigger out the transition of fluids into a turbulent state, subject to a sustained pressure gradient. The present paper explores a computational modeling on two-dimensional fluid flow and thermal characteristics in a bent square channel of strong curvature. The Newton–Raphson (N-R) iteration method is applied to obtain a bifurcation structure depending on the pressure-driven force, the Dean number (De), covering 0 < De ≤ 5000. As a consequence, four branches of asymmetric steady solutions are identified for each of the cases of the Grashof number, Gn (=1000, 1500, and 2000), where only the first branch is found to exhibit asymmetric two-vortex solutions while the remaining branches encompass two- to four-vortex solutions. The similarity and disparity in the branching structure are also demonstrated. Then, adopting the Adam–Bashforth (A-B) method together with Crank–Nicholson (C-N) formula, the unsteady solutions (US) have been explored, validated by power spectrum density (PSD) and phase space Within the realm of US, two- and three-vortex solutions are found and these solutions exhibit transitions from steady to chaotic behavior profoundly. Effects of the Grashof number with convective heat transfer (CHT) are also compared. By analyzing the Nusselt number (Nu), it is observed that in case of highly chaotic flow, CHT experiences substantial enhancement. This intensified CHT arises from increased turbulence and mixing, facilitating more efficient thermal energy exchange under such chaotic flow conditions.

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Numerical study of solution structure and nonlinear behavior of Dean flow with vortex structure in a bending square duct

Hussen,

Islam,

Mondal

2023

Physics of Fluids

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Fluid flow and heat transfer in bending channels are topics of much research interest because of increasing demand in various fields, particularly in the medical and industrial arenas. This paper presents a numerical study of fluid flow and heat transfer in a bending channel with a square cross section. Numerical calculations using spectral methods were performed for a curvature of 0.001 and a Dean number (Dn) in the range of 0<Dn≤5000. A temperature difference was maintained between the horizontal walls for a Grashof number of Gr = 1000, with the bottom wall heated and the outer and inner walls thermally insulated. Applying Newton–Raphson iteration and path continuation, two branching structures of steady solutions with two to eight vortices were obtained. The first branch comprises multi-vortex up to eight and it occurs at Dn≥3500 while the second branch comprises to multi-vortex up to a maximum of four. The first branch forms symmetric solution while the second branch for its complexity forms asymmetric solutions. For unsteady solutions, time-evolution calculations were performed to investigate the nonlinear behavior, and it was found that with increasing Dn, the unsteady flow experienced various flow instabilities. The time evolution was plotted in phase space to clarify the unsteady flow characteristics. Distinctive contours of the secondary flow patterns, streamwise velocity distributions, and isotherms were also obtained, and the unsteady flow was found to comprise two to six vortices. Finally, convective heat transfer was explored by obtaining temperature contours, and the secondary flow was found to magnify the convective heat transfer significantly. Because of the increase of several secondary vortices in the chaotic solutions, heat transfer occurred markedly in the flow.

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Curvature induced instability characteristics of laminar flow and heat transfer through a bent square channel

Cited by 5 publications

References 53 publications

A Computational Study on Fluid Flow and Energy Distribution through a Bending Duct with Longitudinal Vortex Generation

A Computational Study on Fluid Flow and Energy Distribution through a Bending Duct with Longitudinal Vortex Generation

A computational modeling on two-dimensional laminar flow and thermal characteristics through a strongly bent square channel

Numerical study of solution structure and nonlinear behavior of Dean flow with vortex structure in a bending square duct

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