Schlieren Imaging of Viscous Fingering and Buoyancy Driven Convection

Year: 
2017
Ranking: 
Entrant
Artist: 
Simone Stewart
Department: 
Mechanical Engineering
Lab: 
Eckart Meiburg

Description

When a low viscosity fluid (water) is pumped into a high viscosity fluid (95% glycerol 5% water) between a gap only millimeters thick, the result is a fluid instability called viscous fingering. Geometries depend on an array of parameters such as flow speed, gap width, and concentration glycerol.

This viscous fingering image was taken using an optical imaging technique called Schlieren, which consists of a pointed light source, lenses, mirrors and a periscope where the actual experiment takes place. Schlieren is a powerful technique that can detect the difference between two transparent fluids. No dyes or probes needed! Little stripes in each one of the fingers actually appear due to a different fluid instability called buoyancy driven convection, which occurs because the fluids have different densities. The dark rectangle you may notice through the image is the tubing that pumps the less viscous fluid into the system, resulting in the fingering design!

CSEP CNSI Schuller Lab UCSB