Rotations of Large Non-spherical Particles in Turbulence

Many different approaches are used to define scale-local structures which can be used to quantify the multi-scale dynamics of the turbulent cascade.    One very concrete option is to use the rotational motion of rigid bodies.  For example, the tumbling rate of slender fibers has been shown to display inertial range scaling with the mean square tumbling rate scaling as d^-4/3 where d is the fiber length.   A measured particle history provides a sampling of the dynamic evolution of the flow structure at the scale of the particle.   Particle shape plays a central role due to preferential alignment of non-spherical particles by the strain produced by the flow structure.  This talk will discuss what we have learned from measuring rotations of large particles in turbulence and the picture that is emerging from recent numerical and experimental work.