Turbulence and pressure fluctuations in rough wall boundary layers in pressure gradients

The effects of roughness were considered as part of a NATO Advanced Vehicle Technology effort titled "Non-Equilibrium Turbulent Boundary Layers at High Reynolds Numbers" (NATO AVT-349). This paper comments on the current state of understanding of the flow physics and modeling efforts to predict rough-wall boundary layer behavior. Outer layer similarity to smooth wall flows and Reynolds number effects are discussed for zero, favourable, and adverse pressure gradients based on the results of experiments and numerical simulations. Various types of modeling are considered including Reynolds averaged Navier-Stokes (RANS) models with different roughness and turbulence models, wall-modeled large eddy simulations (WMLES), and resolvent models. Current needs and gaps in present understanding are discussed along with recommendations for future experiments and computations.

show abstract

Modeling the Surface Pressure Spectrum on Rough Walls in Pressure Gradients

Fritsch

Vishwanathan

Roy

et al. 2023

Journal of Fluids Engineering

View full text Add to dashboard Cite

Models for surface pressure spectra beneath rough wall boundary layers are assessed, with particular emphasis on prediction from steady, Reynolds-Averaged-Navier-Stokes (RANS) data. RANS roughness boundary conditions are shown to have qualitatively good trends between roughness function and roughness Reynolds number, but model-to-model discrepancies remain and the universality of an equivalent sandgrain roughness height for turbulence models is doubtful. Existing empirical models for the surface pressure spectrum show good agreement in some spectral regions and a newly proposed model shows good matching across the spectrum in a variety of pressure gradient conditions. Adjustments are made to existing TNO analytical models to incorporate rough wall effects, including changes to the velocity spectrum model and the inclusion of a wall-shift, shown to be independent of local Reynolds number, pressure gradient, or turbulence model. The mathematical character of the rough wall spectrum has been revealed, but challenges remain to implement both flow and spectral modeling without a priori knowledge of the flow.

show abstract

Turbulence and pressure fluctuations in rough wall boundary layers in pressure gradients

Cited by 4 publications

References 48 publications

History effects and wall-similarity of non-equilibrium turbulent boundary layers in varying pressure gradient over rough and smooth surfaces

History effects and wall-similarity of non-equilibrium turbulent boundary layers in varying pressure gradient over rough and smooth surfaces

Effects of roughness on non-equilibrium turbulent boundary layers

Modeling the Surface Pressure Spectrum on Rough Walls in Pressure Gradients

Contact Info

Product

Resources

About