Direction change of fluid particles in confined two-dimensional turbulence

etc15 Tracking Number 274

The directional change of a fluid particle can be measured by the angle between two subsequent particle displacement increments. At small values of the time-increment the so-defined angle is proportional to the curvature of the trajectory. At large values this coarse-grained curvature should be affected by the presence of solid no-slip walls around the flow domain. We compare homogeneous and confined two-dimensional turbulent flows and show that the PDF of the angle is indeed strongly modified by the presence of walls.