Rotational Dynamics of Rod Particles in Fluid Flows

Rotational dynamics of rod particles in fluid flows Shima ParsaMoghaddam, Ph.D. Wesleyan University May 2013 The primary aim of this research is to study the dynamics of rods in fluid flows, quantify the alignment of rods with the flow and the effects of alignment on the rotation rates. We perform experimental measurements of the rotation of rods in three-dimensional turbulence and resolve the rotational properties. In a 2D chaotic flow we measured the translational and rotational dynamics of rods along with the velocity of the carrier flow. Rods are strongly aligned with the stretching direction of the Cauchy-Green deformation tensor. We report the first three-dimensional measurements of the rotational dynamics of rod-like particles as they are advected in a turbulent fluid flow. Tracer rods preferentially sample the flow since their orientations become correlated with the velocity gradient tensor. The probability distribution of the mean square rotation rate has a long tail which implies the presence of rare events with large rotation