Probe Jet

Professional Activities

I do experimental research on turbulent shear flows, both bounded and unbounded. In particular my students and I designed and developed a probe to make the first measurements of the full velocity gradient tensor in turbulent flows. Measurements have been carried out in a variety of laboratory and field experiments to gain knowledge of essential properties of turbulence: the vorticity vector, dissipation rate and helicity. These measurements provided a validation of numerical simulations at low Reynolds numbers, extended the range of knowledge about these properties to high Reynolds numbers that are beyond the reach of numerical simulations, and provided insights into the processes that govern the transport of heat, mass and momentum. This research followed my earlier work in Göttingen with Helmut Eckelmann and Bob Brodkey where we were the first to conceive and develop the widely used quadrant analysis of covariance properties of turbulence such as the Reynolds shear stress, heat and mass fluxes, and vorticity covariances. We published the first measurements of the quadrant contributions to the Reynolds shear stress for a channel flow and related them to the coherent motions of this flow.

Additionally, I have investigated scalar dispersion in shear flows with environmental and mixing applications in collaboration with Serge Simöens (Laboratoire de Mécanique des Fluides et d'Acoustique, Ecole Centrale de Lyon/CNRS, France), and developed, with Petar Vukoslavčević (University of Montenegro), methods of measuring turbulence properties in high temperature flows and flows with CO2 as the working fluid.