Experimental setups for studying homogeneous-isotropic and rotating turbulence in clay suspensions: Preliminary results
Homogeneous and isotropic turbulence (HIT) has been at the center of a vast span of research seeking fundamental understanding and insights on the phenomenon of turbulence, which is ubiquitous in nature as well as engineering. The HIT assumption greatly simplifies the analytical treatment of turbulence, however creating truly HIT conditions in experiments has still remained a challenge and most research has focused on Newtonian fluids. Here we uses two different approaches to create HIT in water and aqueous suspension of Laponite clay, a shear-thinning fluid. The first approach involving flow actuators placed symmetrically around an enclosed volume has been used by past studies for creating small regions of HIT in gaseous media. We show using planar particle image velocimetry that our HIT setup is capable of producing low Taylor microscale Reynolds number HIT region of 20 mm x 20 mm in liquid media. Comparison of temporal spectra in water and aqueous clay suspension cases showed that presence of clay significantly alters the scaling of the inertial subrange and increases the Taylor microscale Reynolds number, in addition to suppressing the mean flow. The second approach uses random actuation of jets to stir fluid in a tank, which has been used by past studies to create large HIT regions. We have built a smaller version of this concept with the aim to create high Taylor microscale Reynolds number flow in water and clay suspensions.
Homogeneous-isotropic turbulence, Laponite clay suspension, PIV, non-Newtonian fluid, Taylor-Couette flow
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign