Scaling of velocity fluctuations in off-wall boundary conditions for turbulent flows

1st Multiflow Summer Workshop

Encinar, M.P.^1 ; García-Mayoral, R.^1,2,3 ; Jiménez, J.^1

School of Aeronautics, Universidad Politécnica de Madrid, 28040, Spain^1

Center for Turbulence Research, Stanford University, CA 94305, United States^2

Department of Engineering, University of Cambridge, CB2 1PZ, United Kingdom^3

关键词: Different heights;    Flow fluctuations;    Logarithmic layers;    Pressure fluctuation;    Self-similarities;    Spectral distribution;    Velocity fluctuations;    Wall boundary condition;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/506/1/012002/pdf
DOI  :  10.1088/1742-6596/506/1/012002

来源: IOP

【 摘 要 】

A model for off-wall boundary conditions for turbulent flow is investigated. The objective of such a model is to circumvent the need to resolve the buffer layer near the wall, by providing conditions in the logarithmic layer for the overlying flow. The model is based on the self-similarity of the flow at different heights in the logarithmic layer. It was first proposed by Mizuno and Jime´nez (2013), imposing at the boundary plane a velocity field obtained on-the-fly from an overlying region. The key feature of the model was that the lengthscales of the field were rescaled to account for the self-similarity law. The model was successful at sustaining a turbulent logarithmic layer, but resulted in some disagreements in the flow statistics, compared to fully-resolved flows. These disagreements needed to be addressed for the model to be of practical application. In the present paper, a more refined, wavelength-dependent rescaling law is proposed, based on the wavelength-dependent dynamics in fully-resolved flows. Results for channel flow show that the new model eliminates the large artificial pressure fluctuations found in the previous one, and a better agreement is obtained in the bulk properties, the flow fluctuations, and their spectral distribution across the whole domain.