Session Chair: Ramis Örlü

“Novel volumetric measurement techniques for turbulent flows” by Sigurdur Thoroddsen

The importance of coherent vortical structures for describing turbulence dynamics makes it essential to acquire volumetric measurements of the turbulent velocity fields. Continuing improvement in video camera technology has opened up new possibilities for this purpose. Here, we will describe our measurements of coherent vortical structures in the turbulent flow in a rapid contraction using the Shake-The-Box algorithm while also introducing our own novel techniques. This includes single-camera 3-D particle tracking, using structured illumination to encode the depth location of the particles. The velocity can also be extracted from the time evolution of 3-D scalar fields. Here, we use cross-scanning  LIF to improve the spatial resolution. Finally, the immense pixel-counts of consumer cameras now allow 3-D particle tracking with smartphones and colored shadows. We discuss how this can be used to study flow in different geometries, including pipe flow.