Numerical Analysis of Mixed Convective Heat Transfer from a Square Cylinder Utilizing Nanofluids with Multi-Phase Modelling Approach

Rajendra S. Rajpoot, Shanmugam. Dhinakaran and Md. Mahbub Alam
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Rajendra S. Rajpoot: The Centre for Fluid Dynamics, Department of Mechanical Engineering, Indian Institute of Technology Indore, Simrol, Indore 453552, India
Shanmugam. Dhinakaran: The Centre for Fluid Dynamics, Department of Mechanical Engineering, Indian Institute of Technology Indore, Simrol, Indore 453552, India
Md. Mahbub Alam: Institute for Turbulence Control, Harbin Institute of Technology, Shenzhen 518055, China

Energies, 2021, vol. 14, issue 17, 1-26

Abstract: The present study deals with the numerical simulation of mixed convective heat transfer from an unconfined heated square cylinder using nanofluids (Al 2 O 3- water) for Reynolds number ( Re ) 10–150, Richardson number ( Ri ) 0–1, and nanoparticles volume fractions (?) 0–5%. Two-phase modelling approach (i.e., Eulerian-mixture model) is adopted to analyze the flow and heat transfer characteristics of nanofluids. A square cylinder with a constant temperature higher than that of the ambient is exposed to a uniform flow. The governing equations are discretized and solved by using a finite volume method employing the SIMPLE algorithm for pressure–velocity coupling. The thermo-physical properties of nanofluids are calculated from the theoretical models using a single-phase approach. The flow and heat transfer characteristics of nanofluids are studied for considered parameters and compared with those of the base fluid. The temperature field and flow structure around the square cylinder are visualized and compared for single and multi-phase approaches. The thermal performance under thermal buoyancy conditions for both steady and unsteady flow regimes is presented. Minor variations in flow and thermal characteristics are observed between the two approaches for the range of nanoparticle volume fractions considered. Variation in ? affects C D when Reynolds number is varied from 10 to 50. Beyond Reynolds number 50, no significant change in C D is observed with change in ?. The local and mean Nusselt numbers increase with Reynolds number, Richardson number, and nanoparticle volume fraction. For instance, the mean Nusselt number of nanofluids at Re = 100, ? = 5%, and Ri = 1 is approximately 12.4% higher than that of the base fluid. Overall, the thermal enhancement ratio increases with ? and decreases with Re regardless of Ri variation.

Keywords: nanofluids; mixed convection; mixture model; heated square cylinder; bluff body (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
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