Open Access

ARTICLE

Pressure-Induced Instability Characteristics of a Transient Flow and Energy Distribution through a Loosely Bent Square Duct

Sreedham Chandra Adhikari¹, Ratan Kumar Chanda¹, Sidhartha Bhowmick¹, Rabindra Nath Mondal¹, Suvash Chandra Saha^2,*

1 Department of Mathematics, Jagannath University, Dhaka, 1100, Bangladesh
2 School of Mechanical and Mechatronic Engineering, University of Technology Sydney, New South Wales, Australia

* Corresponding Author: Suvash Chandra Saha. Email:

Energy Engineering 2022, 119(1), 429-451. https://doi.org/10.32604/EE.2022.018145

Received 02 July 2021; Accepted 17 August 2021; Issue published 22 November 2021

Abstract

Due to widespread applications of the bent ducts in engineering fields such as in chemical, mechanical, bio-mechanical and bio-medical engineering, scientists have paid considerable attention to invent new characteristics of fluid flow in a bent duct (BD). In the ongoing study, a spectral-based numerical technique is applied to explore flow characteristics and energy distribution through a loosely bent square duct (BSD) of small curvature. Flow is accelerated due to combined action of the non-dimensional parameters; the Grashof number Gr (=1000), the curvature (=0.001), and the Prandtl number Pr (=7.0) over a wide domain of the Dean number . Fortran code is developed for the numerical computations and Tecplot software with Gost Script and Gost View is used for the post-processing purpose. The numerical study investigates steady solutions (SS) and as a result, a structure of six-branches of SSs composed of 2- to 6-vortex solutions is obtained. Then oscillating behavior with flow transition is discussed by obtaining time-dependent solutions followed by power-spectrum analysis. Results show that the trend of unsteady flow (UF) undergoes in the sequence ‘steady-statemulti-periodicsteady-statechaoticmulti-periodicchaotic’, if Dn is increased. Asymmetric 2- to 4-vortex solutions are obtained for UF. Convective heat transfer (CHT) is then examined obtaining temperature gradients and energy contours, and it is found that CHT is significantly enhanced by the secondary flow (SF). The present study reveals that the role of secondary vortices over heat transfer (HT) is highly significant and HT occurs substantially for the chaotic solutions. Finally, for the interest of validation, the present numerical result is compared with the previously published experimental outcomes, and a good agreement is remarked.

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