Physics and Astronomy Colloquium
		      Tuesday, February 26, 2002
	   4:10 p.m., Room 118 Physics-Astronomy Building

   (Student meeting will be held in Room 224 PA from 3:15-3:45 pm.)

			Eberhard Bodenschatz
			 Cornell University

    Why would a mosquito care about turbulence and why should you?

The motion of fluid particles as they are pushed along erratic 
trajectories by fluctuating pressure gradients is fundamental to transport 
and mixing in turbulence. It is essential in cloud formation, the 
formation of nanoparticles in aerosol reactors; the formation, transport, 
and removal of particulate air pollutants; and multi-phase processes used 
in the chemical industry for heat and mass transfer, and catalytic 
chemical reactions. However, many fundamental issues of particle transport 
in turbulence are unresolved. One such issue is the Heisenberg-Yaglom 
prediction of fluid particle accelerations, based on the 1941 scaling 
theory of Kolmogorov.

Here we report acceleration measurements using a detector adapted from 
high-energy physics to track particles in a high Reynolds number 
laboratory water flow with a very high spatial and temporal resolution. 
We find that universal K41 scaling of the acceleration variance is 
approximately attained at high Reynolds numbers. Our data show very strong 
intermittency-particles are observed with accelerations of up to 1,500 
times the acceleration of gravity (40 times the root mean square value).
We find that the anisotrpy of the flow is present at the smallest scales 
even at very high Reynolds numbers.