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Heat transfer enhancement with additively manufactured rough surfaces: Insights from large-eddy simulations

Garg, Himani LU orcid ; Wang, Lei LU and Fureby, Christer LU (2024) In Physics of Fluids 36(2).
Abstract
To study the impact of additively manufactured (AM) roughness on fluid flow and heat transfer, we performed a series of high-fidelity large-eddy simulations on turbulent heat transfer over a three-dimensional AM rough surface with varying bulk Reynolds number and average roughness height values. We considered rough surfaces created using AM techniques at Siemens based on Nickel Alloy IN939 material with four different mean roughness heights, ks = 1.594, 1.992, 2.630, and 3.984 mm, and the simulations were performed at five bulk Reynolds numbers of 1000, 3000, 6000, 11 700, and 18 000. The temperature was treated as a passive scalar with a Prandtl number of 0.71. To better understand the effect of wall roughness on the momentum and heat... (More)
To study the impact of additively manufactured (AM) roughness on fluid flow and heat transfer, we performed a series of high-fidelity large-eddy simulations on turbulent heat transfer over a three-dimensional AM rough surface with varying bulk Reynolds number and average roughness height values. We considered rough surfaces created using AM techniques at Siemens based on Nickel Alloy IN939 material with four different mean roughness heights, ks = 1.594, 1.992, 2.630, and 3.984 mm, and the simulations were performed at five bulk Reynolds numbers of 1000, 3000, 6000, 11 700, and 18 000. The temperature was treated as a passive scalar with a Prandtl number of 0.71. To better understand the effect of wall roughness on the momentum and heat transfer mechanism, mean temperature and velocity profiles as well as heat fluxes are presented. The wall-normal Reynolds stress, ⟨u_x^' u_r^'⟩⁠, and heat flux, ⟨u_r^' Θ'⟩⁠, decrease for larger wall roughness heights, Ra, and their respective magnitudes remain very similar for different Ra. A similarity rule for friction factor and heat transfer is used to correlate and interpret the numerical results and compare them with previously existing results, both theoretical and experimental. The assessment of the thermal performance factor illuminates the improvement in heat transfer with the existing surface roughness. By studying the probability density functions of the instantaneous Stanton number, the recirculation zones, which are the result of an adverse pressure gradient, were found to have a profound effect on heat transfer. This is important as it leads to the wall-scaled mean temperature profiles being of larger magnitude than the mean velocity profiles both inside and outside the roughness layer. This means that the temperature wall roughness function, ΔΘ^+⁠, differs from the momentum wall roughness function, ΔU^+⁠. (Less)
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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Heat transfer, Turbulent flows, Turbulence simulations, Fluid drag, Aerodynamics, Computational fluid dynamics, Fluid mechanics, 3D printing
in
Physics of Fluids
volume
36
issue
2
article number
025109
publisher
American Institute of Physics (AIP)
external identifiers
  • scopus:85184142609
ISSN
1070-6631
DOI
10.1063/5.0189115
language
English
LU publication?
yes
id
867c9830-fb11-40e0-b9e9-3c6d18cfba23
date added to LUP
2024-02-12 10:17:17
date last changed
2024-02-16 13:11:59
@article{867c9830-fb11-40e0-b9e9-3c6d18cfba23,
  abstract     = {{To study the impact of additively manufactured (AM) roughness on fluid flow and heat transfer, we performed a series of high-fidelity large-eddy simulations on turbulent heat transfer over a three-dimensional AM rough surface with varying bulk Reynolds number and average roughness height values. We considered rough surfaces created using AM techniques at Siemens based on Nickel Alloy IN939 material with four different mean roughness heights, ks = 1.594, 1.992, 2.630, and 3.984 mm, and the simulations were performed at five bulk Reynolds numbers of 1000, 3000, 6000, 11 700, and 18 000. The temperature was treated as a passive scalar with a Prandtl number of 0.71. To better understand the effect of wall roughness on the momentum and heat transfer mechanism, mean temperature and velocity profiles as well as heat fluxes are presented. The wall-normal Reynolds stress, ⟨u_x^' u_r^'⟩⁠, and heat flux, ⟨u_r^' Θ'⟩⁠, decrease for larger wall roughness heights, Ra, and their respective magnitudes remain very similar for different Ra. A similarity rule for friction factor and heat transfer is used to correlate and interpret the numerical results and compare them with previously existing results, both theoretical and experimental. The assessment of the thermal performance factor illuminates the improvement in heat transfer with the existing surface roughness. By studying the probability density functions of the instantaneous Stanton number, the recirculation zones, which are the result of an adverse pressure gradient, were found to have a profound effect on heat transfer. This is important as it leads to the wall-scaled mean temperature profiles being of larger magnitude than the mean velocity profiles both inside and outside the roughness layer. This means that the temperature wall roughness function, ΔΘ^+⁠, differs from the momentum wall roughness function, ΔU^+⁠.}},
  author       = {{Garg, Himani and Wang, Lei and Fureby, Christer}},
  issn         = {{1070-6631}},
  keywords     = {{Heat transfer; Turbulent flows; Turbulence simulations; Fluid drag; Aerodynamics; Computational fluid dynamics; Fluid mechanics; 3D printing}},
  language     = {{eng}},
  month        = {{02}},
  number       = {{2}},
  publisher    = {{American Institute of Physics (AIP)}},
  series       = {{Physics of Fluids}},
  title        = {{Heat transfer enhancement with additively manufactured rough surfaces: Insights from large-eddy simulations}},
  url          = {{http://dx.doi.org/10.1063/5.0189115}},
  doi          = {{10.1063/5.0189115}},
  volume       = {{36}},
  year         = {{2024}},
}