Issues with 'cmue_a'
Boqi Boqitian@UW.Edu
Hi Lars, Hans and GOTM,
We are trying to integrate the “non-local, exact weak-equilibrium stability function” (after Gibson and Launder, 1976, per GOTM manual) into another model nonlocal with another closure we have been working on that accounts for some pressure-strain terms near boundaries.
When we look at corresponding source code 'cmue_a.F90' we see it's in a “testing stage”, apparently since 2005.
We note a sequence of two lines where the second overrides the first, which is more faithful
Nt = 0.5*(Pe-1.) + ct1 + 0.5*r_i*(Pbeb - 1.) ! general
Nt = (Pe-1.) + ct1 ! weak equilibrium
We also note there is no constraint related to realizability or stability in cmue_a as there is e.g. in the weak equilibrium (cmue_c) or quasi-equilibrium (cmue_d) code.
Can anyone recall and relate experience working with cmue_a two decades ago? Was there any conceptual or numerical problem in particular that hindered carrying this integration into GOTM forward, or are we reading too much in between those contradictory lines of code?
Is anyone else currently working on this? Perhaps in follow-on to Legay, Deremble & Burchard (2025: https://doi.org/10.1029/JC095iC09p16179 )?
Thanks.
Regards,
Kevin Tian & Ramsey Harcourt
University of Washington
Lars Umlauf
Hi Kevin and Ramsey,
As far as I know, nobody has really worked on these parts of the code since I've implemented them into GOTM many years ago. Hans and I basically never found the time to follow up on this because other things came up.
As shown by Legay et al. (2005), including this non-local
framework in closure models improves the surface-layer structure
especially during convection, and I am convinced this also applies
to other non-local processes like LT. So it is really great that
you're working on this type of models. I hope we can talk about
this at the WTD.
All the best,
Lars
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-- ------------------------------------------------ Lars Umlauf Department of Physical Oceanography Leibniz-Institute for Baltic Sea Research phone : ++49 381 5197 223 fax : ++49 381 5197 114 web : www.io-warnemuende.de/lars-umlauf-en.html address: Leibniz-Institute for Baltic Sea Research Seestrasse 15 D-18119 Rostock-Warnemuende Germany -------------------------------------------------
Helmut Z. Baumert
attached please find an older paper where the physical background of
turbulence modeling is discussed at Re=\infty. It gave reasonable
ANALYTIC results for a number of well-known universal constants, e.g.
for von Karman's constant as 1/SQRT(2\pi)=0,398 ...~ 0,40.
Also other constants like pre-factors of the Kolmogoroff's frequency and
wave-number spectra are given, close to the observed/measured values in
super-pipes.
I remember that a plausible value for c_mue as
1/\pi_squared ~ 0,101... resulted from that theory, but was not yet
included in the attached paper due to other obligations. If you will
approach the problem in students's PhD theses, please let me know ...
Best regards,
Helmut Z. Baumert
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