Direct Numerical Simulation of Thermal Turbulent Boundary Layer Flow over Multiple V-Shaped Ribs at Different Angles

Feng Ji, Jing Ding, Jianfeng Lu () and Weilong Wang ()
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Feng Ji: School of Intelligent Systems Engineering, Sun Yat-sen University, Shenzhen 510275, China
Jing Ding: School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
Jianfeng Lu: School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
Weilong Wang: School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China

Energies, 2023, vol. 16, issue 9, 1-22

Abstract: Direct numerical simulations (DNSs) of spatially developing thermal turbulent boundary layers over angle-ribbed walls were performed. Four rib angles ( γ = 90 ° , 60 ° , 45 ° and 30 ° ) were examined. It was found that the 45 ° ribs produced the highest drag coefficient, whereas the 30 ° ribs most improved the Stanton number. In comparison to the transverse rib case, streamwise velocity and dimensionless temperature in the V-shaped cases significantly increased in the near wall region and were attenuated by secondary flows further away from the ribs, which suggested a break of the outer-layer similarity in the scenario presented. The surprising improvement of heat transfer performance in the 30 ° rib case was mainly due to its large dispersive heat flux, while dispersive stress reached its peak value in the 45 ° case, emphasizing the dissimilarity in transporting momentum and heat by turbulence over a ribbed surface. Additionally, by calculating the global and local Reynolds analogy factors, we concluded that the enhancement in heat transfer efficiency was attributed to an increasing Reynolds analogy factor in the intermediate region as the rib angle decreased.

Keywords: direct numerical simulation; thermal turbulent boundary layer; ribbed surface; heat transfer; Reynolds analogy (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: 2023
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