Marangoni shocks in unobstructed soap-film flows.
It is widely thought that in steady, gravity-driven, unobstructed soap-film flows, the velocity increases monotonically downstream. Here we show experimentally that the velocity increases, peaks, drops abruptly, then lessens gradually downstream. We argue theoretically and verify experimentally that the abrupt drop in velocity corresponds to a Marangoni shock, a type of shock related to the elasticity of the film. Marangoni shocks induce locally intense turbulent fluctuations and may help elucidate the mechanisms that produce two-dimensional turbulence away from boundaries.
Tran
Tuan
T
Department of Mechanical Science and Engineering, University of Illinois, Urbana, Illinois 61801, USA.
Chakraborty
Pinaki
P
Gioia
Gustavo
G
Steers
Stanley
S
Goldburg
Walter
W