[rdemyan]

For my experimental data, the turbulent kinetic energy, k, calculated from the energy spectrum varies by up to plus or minus 50% from the TKE calculated from the energy dissipation rate. It's strange because the calculated cumulative dissipation from the spectrum typically matches the energy dissipation rate to within plus or minus 10% for all of my experimental data. I would have thought that the comparison of TKE and the comparison of %cumulative dissipation would be comparable (i.e each comparison to within 10%). After all, the non-spectrum determination of the TKE comes from the energy dissipation rate.

[LuckyTran]

tke is calculated from rmse of the velocity. Why even bother doing it any other way?


TKE is not calculated from dissipation rate. See the wiki for an example of how to calculate tke, only the first formula. The 2nd and 3rd are examples of averages. You can ignore the rest of the article.

[rdemyan]

Originally Posted by LuckyTran

tke is calculated from rmse of the velocity. Why even bother doing it any other way?


TKE is not calculated from dissipation rate. See the wiki for an example of how to calculate tke, only the first formula. The 2nd and 3rd are examples of averages. You can ignore the rest of the article.

Actually, I calculate the TKE from the velocity differences of impinging sheets and it is a highly accurate calculation. I've already sent you links on the work in private messages and I don't want to reveal my name on this blog. So, you can check that out if you are interested.

That TKE number is then used to calculate the energy dissipation rate. For experimental work, this is the way I think it would be done, but if you are given the energy dissipation rate, you can back out the TKE from the following formula:

TKE ~ (L)^2/3

where L is the large scale eddies in the production range.

So forget my statement regarding calculating it from the energy dissipation rate, if it bothers you. I actually determine it directly and it is highly accurate.

It still doesn't change the fact that I'm getting this discrepancy. Any thoughts on that? It might be that Pope's method for calculating TKE is a bit different from mine. But still, I don't understand why the comparison of cumulative dissipation with energy dissipation rate would be within 10% for over 100 runs, yet, the comparison of TKE calculations is only to within 50%. The formula for D() uses E(), so.....

[LuckyTran]

It's only fair that you reveal your name if I reveal my name. You should own up to your ideas. No one here claims ownership of your ideas so it is no loss to you.

I don't read pm's. I've never had an intellectual conversation that occurred in pm's.


Still, energy dissipation rate is not tke, that should be clear. Dissipation rate is also not energy spectrum.


I assure you that Pope's definition of tke is the same as mine and everyone else's. If you think otherwise, then there isk a misunderstanding or a lapse in your understanding.

[rdemyan]

Originally Posted by LuckyTran

It's only fair that you reveal your name if I reveal my name. You should own up to your ideas. No one here claims ownership of your ideas so it is no loss to you.

I don't read pm's. I've never had an intellectual conversation that occurred in pm's.


Still, energy dissipation rate is not tke, that should be clear. Dissipation rate is also not energy spectrum.


I assure you that Pope's definition of tke is the same as mine and everyone else's. If you think otherwise, then there isk a misunderstanding or a lapse in your understanding.

This is an absurd answer. Where did you reveal your name and it's not even on point. Do me a favor and don't reply to my posts anymore.

[LuckyTran]

Here's is what potentially might happen assuming your intellectual thoughts are 100% accurate and Pope is 100% wrong all the time. You are going to publish the paper that you sent me. The reviewer will say, wait a minute, there is an rdemyan from the internet who published these exact thoughts in an internet forum, your work is not original, reject. We don't do ghost writers and pennames, the last such case was student.


But you are right that your name has nothing to do with how tke should be calculated so why even bring it up. Saying hey yo, I sent this paper of how I have a novel definition of tke to a guy on an internet forum is not a proof that you are calculating tke in any meaningful way. It's hearsay. tke is rmse of velocity or rms of u', v', and w', and then 1/2. And then you calculate the spectrum of these square fluctuations except not averaged in time. How you are calculating dissipation rate from energy spectrum and then calculating k from dissipation rate. You have created your own chicken and egg paradox.

[rdemyan]

Learn to read. I never said TKE was the same as the energy dissipation rate. I said it could be back-calculated from the energy dissipation rate. Then I said I first calculate the TKE to use in an equation for calculating the energy dissipation rate. Further, the paper I sent you is on a preprint server, which given your response is something you are not familiar with. At any rate, this is the last time I will respond to you and again please don't respond to my posts.

[LuckyTran]

I didn't even read the paper so I have no clue what is in it. It could be a virus for all I know. Merely pointing out it doesn't develop the discussion to include hearsay.