G. Lemonis, 3-DIMENSIONAL MEASUREMENT OF VELOCITY, VELOCITY-GRADIENTS AND RELATEDPROPERTIES IN TURBULENT FLOWS, Aerospace science and technology, 1(7), 1997, pp. 453-461
A finite difference method for the simultaneous measurement of the thr
ee-dimensional velocity vector and its gradient tensor in turbulent ai
rflow is presented and verified. The method relies upon the simultaneo
us measurement of the velocity vector at different locations of the fl
ow field using a twenty-hotwire probe consisting of five orthogonal fo
ur-hotwire subprobes. Evaluation of velocity vectors for each subprobe
is performed in three-dimensional space using a trivariate approximat
ion procedure of the probe calibration data. With this technique exten
sive measurements of three-dimensional velocity, its spatial derivativ
es and other related properties as three-dimensional vorticity, local
dissipation, vorticity production and turbulent length scales have bee
n carried out in the wind tunnel. The flows investigated have been qua
si-isotropic turbulent grid flow and turbulent boundary layer at moder
ate Reynolds numbers. The results obtained are satisfactory and in goo
d agreement to theory and ether experimental and computational investi
gations known from literature.