Another Timoshenko medal, this time to John L. Lumley

In order to ‘complete’ the list of the previous posts, the medal was given to John L. Lumley in 1993. He’s, among many other things, maybe the most cited author in my publications (see some of them here) and also one of the authors of the course book (I teach Introduction to Turbulence for graduates this spring) – “A first course in turbulence” by Tennekes and Lumley (here is the link, great book)

a small part of his lecture is quite interesting story about a practical problem that was understood by solving a fluid-mechanics puzzle:

Sometimes it is like detective work. Let me tell you about something I worked on last year, that will illustrate how a complex, interdisciplinary practical problem can lead to fundamental problems. This is in the area of atmospheric turbulence, in which I worked for some years at Penn State. Some of the material may be unfamiliar, but I think you will find the logical chain interesting. My client was a sheep farmer whose sheep seemed to be dying as a result of emissions of sulfur dioxide and hydrogen sulfide from a heavy water plant. Both sulfur dioxide and hydrogen sulfide are toxic in sufficiently high concentrations. The farmer was just a kilometer and a half from the plant, which is very close, but any normal calculations suggested that his sheep were receiving concentrations at a level considered completely safe. In addition, monitoring stations placed near his farm indicated low concentrations. I must explain how Hydrogen sulfide and sulfur dioxide happened to be emitted. Hydrogen sulfide is used in the process of making heavy water, and once a year the towers in which the heavy water is made have to be cleaned. After as much hydrogen sulfide as possible has been removed from the towers, the majority of the remainder is burned on a flare stack and converted to sulfur dioxide. The plant was right on the edge of one of the great lakes, and the stack was close to the water. After several false starts, we finally realized that the on-shore breeze from the lake, during the spring and summer, was stably stratified, and thus not turbulent, from traveling over the cooler lake water for hundreds of kilometers. The top of the stack was in this stably stratified air. Thus, the stack plume did not disperse. The cool, stable air, when it started over the warmer land, began to grow an internal turbulent boundary layer, and when this reached the height of the stack plume, the plume was sucked into the first downgoing eddy, and taken to the surface. The distances were about right so that the place where this happened was right over my client’s farm, and the first descending eddy was probably caused by his cool, insulated farm buildings. His sheep were thus getting the stack plume at nearly full strength. The plume, of course, did not descend on the monitoring station. The matter was complicated by the fact that the sulfur dioxide was considerably heavier than air, and could lie on the ground in hollows among the vegetation, where the sheep would be immersed in it.

This general situation is called shoreline fumigation, and is well-known to meteorologists. However, they are only familiar with the average effects. The phenomenon of the descent of the instantaneous plume to ground level, with its associated high instantaneous concentrations, has not been measured. One of my colleagues has now submitted a proposal for laboratory measurements of instantaneous concentrations in this situation. In addition, the pooling of the sulfur dioxide at ground level, and the probability of its remaining for various periods, was a nice little fundamental problem that was fun to solve.

Everything has its down side, and I must admit I don’t much like being questioned in hearings. In addition, this was all part of an environmental impact hearing in connection with a request for license renewal for the heavy water plant. When it became evident that my client had a case that would stand up, the request for license renewal was withdrawn. As a result, the outcome is moot. Also, although I work hard at communicating my results, I sometimes suspect that my clients find my name and credentials more useful to them than my findings. That’s all right – at least I had fun.


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