Tuesday, October 21, 2008

Turbulent Natural Convection

A long long time ago, when I was a graduate student at IIT Madras, I had taken a course on turbulence, and pretty much fell in love with the physics of turbulent flow.

I was already in love with natural convection - which I found fascinating - right from my undergraduate years - when our professor did a splendid job in teaching us the same. (Some "good professors" of IIT Madras are probably among the best philosophers in the world!)

Since I was in love with these subjects, in all naivete, I had put in "turbulent natural convection" as field of interest while applying for higher studies (PhD) in the US three years ago.

When I wound up here at Texas A&M, I worked on turbulent flow on the experimental side. As "application engineers", we really don't worry about quantities such as Reynolds Stresses and Turbulent Kinetic energies. We deal with deliverable and tangible quantities such as the skin friction coefficient and heat transfer coefficient. As far as experiments are concerned, the Reynolds stress might as well just go hang itself.

This is, of course, a fascinating line of inquiry. The kind of work we do is so miserably turbulent, it would be foolhardy to even try to predict some of our results analytically. This justifies our existence as experimenters. It is fascinating to note that computational tools are doing a pretty good job of reproducing experimental data.

Now, then, let's not digress. So, here I am, working on high Reynolds numbers. Such right reynolds numbers that Buoyancy does not stand a chance.

We also deal with rotating systems - which are subject to coriolis and Centrifugal forces. The centrifugal force acts like buoyancy - but for the ranges which we were studying, its effect was not that profound.

But a closer examination of experimental data indicated that it is INDEED affecting playing a significant role - we just did not know it. There's probably a nice natural convection boundary layer that set iself up in our test section - but we just did not have the resources to identify it.

Things have a bizzare way of coming true. I wanted to work on turbulent natural convection. I am working on something more complex turbulent natural convection: turbulent "mixed" convection. Just not in the way I would have visualized earlier.

(In another bizzare irony, the wife, incidentally works on transitionary natural convection all the time as she tries to clone her DNA in her lab).

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