Internal Seminar: Noa Burshtein, Student, Micro/Bio/Nanofluidics Unit (Shen Unit)

Internal Seminar: Noa Burshtein, Student, Micro/Bio/Nanofluidics Unit (Shen Unit)

Title: Controlling vorticity onset and growth with polymers

Abstract: It was discovered in the late 1940’s that the addition of small quantities of polymers to a turbulent flow of Newtonian fluid (e.g. water) can result in a very significant reduction in drag. This discovery has widespread applications such as improving pumping efficiency in oil pipelines, increasing sewer capacity during heavy rainfall, and improving blood circulation. However, the mechanisms underlying how polymer additives enhance flow are complex and many questions remain to be resolved. Since turbulent flows are characterized by the presence of vortices, understanding how the addition of polymers affects the formation of vortices may be one key to understanding polymer drag reduction. Unfortunately, in general vortices are difficult to study under well-controlled conditions. In this presentation, we will first describe our recent discovery of how a single steady-state vortex can be generated for a simple Newtonian fluid flow in a microfluidic “cross-slot” geometry, and our subsequent development of novel methods allowing quantitative measurements of the velocity field within the vortex. Finally, we are able to show clearly how the formation and development of a vortex is significantly altered by the addition of even tiny quantities of polymers (as little as 1 part-per-million), which are typical quantities used in drag reduction applications.

Refreshments will be served afterwards. We hope to see you there! 

Sincerely,  

Internal Seminar Organizing Committee: 

Marylka Yoe Uusisaari
Yasha Neiman 
Rob Campbell 
Margaret Mars Brisbin 
Maéva Techer 
Jigyasa Arora
Yuka Suzuki
Andreas Thomasen
Kun-Lung Li