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P-23 Extreme Fluids Team

  
 
 

Instabilities, Mixing & Turbulence                  

We are performing high-resolution experiments to understand mixing transition and turbulence. There are many unanswered questions:

• What is the nature of turbulence and mixing in a multi-material, density stratified flow?

• How does the flow mix?  How do we quantify mixing?

• What are the effects of Mach number on mixing of shocked flows? 

• How do frequencies and amplitudes of perturbations in the initial conditions impact the mixing?

 

              

Horizontal Shock Tube Facility

  
   

At the Horizontal Shock Tube Facility, we study the mixing after a shock impacts a heavy gas curtain of SF6 using Particle Image Velocimetry (PIV) to measure the 2-D instantaneous velocity field, and Planar Laser Induced Fluorescence (PLIF) to measure the instantaneous 2-D density field.

  
               
PLIF images of a shocked, varicose curtain of SF6 show the instabilities created when a Mach 1.5 shock wave hits the perturbed curtain. These images, part of the dissertation work of Greg Orlicz, capture the late-time mixing of the gas curtain with unparalleled resolution.              

PIV measurements of a reshocked gas curtain, 385 µs after reshock, allow us to calculate the magnitude of the turbulent kinetic energy across the mixing region, as well as providing information about the velocity fluctuations. This work is part of the postdoctoral research of Sridhar Balasubramanian, and part of our Laboratory Directed Research and Development project, "Turbulence by Design."