Representation of Surface Roughness in Hybrid Turbulence Simulations

The influence of surface roughness on overlying turbulence is represented by a drag layer, with a quadratic drag law. The drag coefficient is considered to be a function of effective sandgrain roughness. The challenge to hybrid modeling is posed as being to calibrate that drag law, such that the cal...

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Bibliographic Details
Published inFlow, turbulence and combustion Vol. 109; no. 2; pp. 255 - 277
Main Authors Varghese, Joel, Durbin, Paul A.
Format Journal Article
LanguageEnglish
Published Dordrecht Springer Netherlands 01.08.2022
Springer Nature B.V
Subjects
Automotive Engineering
Boundary conditions
Boundary layers
Calibration
Drag coefficients
Engineering
Engineering Fluid Dynamics
Engineering Thermodynamics
Fluid- and Aerodynamics
Heat and Mass Transfer
Surface roughness
Turbulence
Turbulent boundary layer
Equivalent sandgrain roughness
Detached eddy simulation
Discrete element model
Hybrid simulation
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Summary:The influence of surface roughness on overlying turbulence is represented by a drag layer, with a quadratic drag law. The drag coefficient is considered to be a function of effective sandgrain roughness. The challenge to hybrid modeling is posed as being to calibrate that drag law, such that the calibration be nearly the same for either RANS or LES. To that end the coefficient is first calibrated for LES. With roughness represented by the drag formula, the RANS model and boundary condition are adjusted to provide consistency in the log layer. Then, it is found that RANS and LES calibrations become nearly the same. The model is validated by simulations of a rough wall boundary layer, of rough to smooth junction flow, of a rough ramp, and of streamwise roughness strips.
ISSN:1386-6184
1573-1987
DOI:10.1007/s10494-022-00333-x