On estimating mean and instantaneous turbulent energy dissipation rates with hot wires

The hot wire continues to be a useful tool for investigating small-scale properties of turbulence. This paper examines some of the remaining difficulties associated with the use of hot wires for achieving adequate approximations to either the instantaneous energy dissipation rate epsilon or its mean value [epsilon]. Several hot wire geometries are considered, ranging, in order of increasing complexity, from a single hot wire placed normal to the flow to a combination of four X-wires acting as 3-component vorticity probe. A probe of intermediate complexity, which combines an X-wire with a pair of parallel wires, may provide a realistic compromise in terms of approximating epsilon and [epsilon] adequately. (C) 2003 Elsevier Science Inc. All rights reserved.