Statistics of filtered velocity in grid and wake turbulence


Stefano Cerutti & Charles Meneveau
Department of Mechanical Engineering
The Johns Hopkins University
Baltimore MD 21218

ABSTRACT: Data on spatially filtered turbulence are commonly needed for a priori sub-grid model studies and for a posteriori testing of Large Eddy Simulation (LES)codes. In this paper, hot-wire anemometry is used to record very long records of such data, required for good convergence of high-order statistics. An array consisting of four X-wire probes placed transversal to the flow direction is built. Unlike previous single-probe hot-wire measurements, which only allowed stream-wise filtering using Taylor's hypothesis, the array permits cross-stream filtering as well. Measurements which are spatially filtered at a length-scale pertaining to the inertial-range of turbulence are performed in grid and wake turbulence. The data can be used directly to compare with results from LES. From the data, fundamental differences between filtered and unfiltered velocity fields are examined through probability density functions and the scaling behavior of high-order structure functions. A comparative study of probability density functions of filtered and unfiltered velocity increments shows that the tails of the distributions are affected by the filtering even at scales much larger than the filter scale. Significant differences are also observed in regard to the scaling of structure functions. It is shown that Extended Self-Similarity, a recent technique for measuring inertial range scaling exponents, yields questionable results when applied to structure functions of filtered velocity.

Phys. Fluids 12, p. 1143 (2000)

full pdf article (©AIP, see http://www.ojps.aip.org/phf)

(Reused with permission from Stefano Cerutti, Physics of Fluids, 12, 1143 (2000). Copyright 2000, American Institute of Physics.)

§ Archival Journal Publications: Articles may be downloaded for personal use only!
Any other use requires prior permission of the Author and the Publishers.

 

Charles Meneveau, Department of Mechanical Engineering, Johns Hopkins University, 3400 N. Charles Street, Baltimore MD 21218, USA, Phone: 1-410-516-7802, Fax: 1-(410) 516-7254, email: meneveau@jhu.edu

  
Last update: 03/17/2011