Binormal cooling errors in single hot-wire measurements

Authors: Örlü, R., Alfredsson, P.H.
Document Type: Article
Pubstate: Published
Journal: J. Theor. App. Mech. Pol.
Volume: 54   305-310
Year: 2016


In single-wire hot-wire measurements, velocity fluctuations acting normal to the hot-wire and its prongs will cause additional heat transfer known as binormal cooling. With respect to wall turbulence, the influence of this additional cooling is well-studied for crossed wires, while it is commonly ignored in single hot-wire measurements. The latter view is challenged in the recent work by Dró?d? and Elsner (2014) that claims significant errors in variance measurements when using single-wire probes in turbulent boundary layers. This short communication revisits these claims and quantifies binormal cooling errors through an expansion of the effective-velocity concept and utilisation of direct numerical simulation data. Results support the common habit that binormal cooling errors can safely be ignored in single hot-wire measurements.