School of Physics Nonlinear Science & Mathematical Physics WEBINAR: Presenting Sam Raben, Virginia Tech

Scientists for years have been trying to better understand the mechanisms that are responsible for transport and mixing in fluid flow.  Mixing is important as it is used in everything from food preparation to energy production to biomedical devices, and is seen in both single and multiphase environments.  While mixing applications are wide ranging, a complete and proper understanding of mixing and transport mechanisms is still lacking.  These mechanisms are influenced by, but not limited to, time varying structures that may be seen in flow.  Addressing this deficit in our knowledge requires improved techniques for quantifying transport and mixing. 

One way in which these transport structures can be more accurately resolved is by investigating time-resolved fluid element trajectories as opposed to the current method of numerical integration of velocity fields.  By following the flow tracers, which have a similar behavior to that of the fluid elements, there is no need for numerical integration, which can introduce noise and error into the trajectories.  These fluid element surrogates may be neutrally buoyant tracer particles but also inertial elements like bubbles or large Stokes number solid particles, which will reveal different types of structures in the flow.  It has been shown that time varying coherent structures in fluid flow can have an important effect on the mixing behavior of a system.  Through the use of fluid element trajectories these time varying structures can be directly studied with the hope that this will aid in the understanding of mixing and transport in three-dimensional flow fields.