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Commit 88dba473f060 authored by Pierre Augier's avatar Pierre Augier
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tmp after conf Nice

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......@@ -45,8 +45,12 @@
hyperdiffusion?
}
We performed with Jason Reneuve an extensive study on dealiasing methods
(also with phase shifting). It is not yet published but a notable result is that ... TODO...
\itemit{p.5: what is the motivation behind forcing low frequency waves only? Wouldn't
it be better to increase the wave frequency to better satisfy the timescale
separation required by WWT?
}
......@@ -48,8 +52,11 @@
\itemit{p.5: what is the motivation behind forcing low frequency waves only? Wouldn't
it be better to increase the wave frequency to better satisfy the timescale
separation required by WWT?
}
TODO: add in the article + add added text here. (geophysical fluids (for example M2 waves) + temporal spectra)
\itemit{
Why is hyperviscosity added to the regular viscosity? Is it just for
regularisation purposes, but in that case, the simulations presented cannot be
......@@ -57,9 +64,20 @@
would they all blow up without it?
}
TODO: add in the article + add added text here.
- Most of the simulations are proper DNS with $\kmax\eta$ larger or close to one. For example (40, 20), $\kmax\eta = 0.99$ and 1.05.
- Few simulations are not DNS, but they can be to some extend characterized with the standard Reynolds number.
- Without hyperviscosity the simulations would not blow up.
- Dataset which can be later improved...
\itemit{
Shear modes are removed from all simulations, but how is this achieved
exactly? Is it done via a spectrally localised damping term or simply put to
zero at every time steps?
}
......@@ -60,9 +78,14 @@
\itemit{
Shear modes are removed from all simulations, but how is this achieved
exactly? Is it done via a spectrally localised damping term or simply put to
zero at every time steps?
}
TODO: add in the article + add added text here.
Put to zeros at each time step. Conserves energy. Similar physically to vertical walls in a tank.
\itemit{
It is mentionned that the forcing is not delta-correlated in time but that
its correlation time is consistent with the dispersion relation of internal
......@@ -74,6 +97,18 @@
change something to the results presented here?
}
TODO: describe better the forcing in the article + add added text here.
- no proper stochastic process involve. Phase and amplitude of the forced wavenumbers random and changed in time ...
- a bit of Python to compute time spectra of such process.
- this aspect of the forcing will be discussed in a paper describing more globally the dataset.
TODO: add the question on possible effect of harmonic forcing. We don't know.
Interesting open question that could be investigated in future studies.
\itemit{
Figure 7: could you show the spatial structure of the dominant vortical mode
by filtering the coefficients in Fourier space and transform it back to physical
......@@ -81,7 +116,10 @@
and without vortical modes, would be helpful in my opinion.
}
Add a 3D figure...
\itemit{
Figure 9: what is the purpose of the kz=kh line?
}
......@@ -84,7 +122,10 @@
\itemit{
Figure 9: what is the purpose of the kz=kh line?
}
?
\itemit{
Figure 16: this is an important plot in my opinion, it might be useful to
include other studies? In particular, it is rather suprising that [46] is so far
......@@ -93,9 +134,16 @@
filling the gap between these two extremes?
}
TODO: which studies with wave forcing? Waite... Lindborg... ???
For studies motivated by geophysical flows, the focus is more on buoyancy Reynolds number large or at least not very small.
Unfortunately, not always easy to correctly quantify these numbers from the data given in the articles.
\itemit{
The shear modes are always suppressed while the vortical modes are either
left or suppressed. Do the authors expect surprising behaviours with the shear
modes but without the vortical modes?
}
......@@ -96,9 +144,14 @@
\itemit{
The shear modes are always suppressed while the vortical modes are either
left or suppressed. Do the authors expect surprising behaviours with the shear
modes but without the vortical modes?
}
We know thanks to a study on 2D turbulence (Calpe-linares PhD thesis)
that shear modes can grow without toroidal modes. Therefore we can anticipate accumulation of energy in shear modes,
which should become very strong and distore the waves.
\itemit{
Note that Le Reun et al. [46] did not have to remove neither shear nor
vortical modes (while the same authors had to remove the geostrophic flow in
......@@ -110,5 +163,7 @@
grow if not directly forced?
}
TODO: improve the discussion on the difference between Le Reun et al.
\end{enumerate}
......@@ -113,6 +168,5 @@
\end{enumerate}
\subsection*{Additional small comments:}
\begin{itemize}
......
......@@ -52,6 +52,9 @@
and why, and how $n_z$ is chosen.
}
TODO: better describe in the method section.
\itemit{
The poloidal forcing is meant to excite only waves but you do not discuss
its impact on the potential vorticity (PV), which governs the vortical mode. In
......@@ -59,6 +62,14 @@
given how important a concept it is in geophysical fluid mechanics.
}
PV is known to be much less dynamically important in stratified flows than in stratified and rotating flows.
The Ertel PV $\bomega \cdot \bnabla (N^2 z + b) = \omega_z (N^2 + \partial_z b) + \bomega_h \cdot \bnabla_h b$
is not quadratic and is not equal to the Charney PV.
There is no PV cascade like in quasi-geostrophic flows.
The forcing in poloidal velocity produces and removes PV but we do not know what can be deduced from that.
\itemit{
I felt overwhelmed by the great number of non-dimensional parameters
introduced here; even with all these definitions one could still invent more, ie
......@@ -69,8 +80,15 @@
unfolded.
}
- Improve eq (17)
- Move end of page 7 later...
- No non-dimensional numbers based on hyper-viscosity ...
\itemit{
You talk of “removing vortical modes”. How is that done numerically? Is it
a similar process as in Holmes-Cerfon et al. in JFM 2013?
}
......@@ -72,11 +90,14 @@
\itemit{
You talk of “removing vortical modes”. How is that done numerically? Is it
a similar process as in Holmes-Cerfon et al. in JFM 2013?
}
TODO: improve the method section.
\itemit{
In the discussion session you say that the energy conversion rate does not
fluctuate around zero. As only the kinetic energy is forced, shouldn’t the
KE->PE conversion rate be nonzero a priori?
}
......@@ -77,9 +98,12 @@
\itemit{
In the discussion session you say that the energy conversion rate does not
fluctuate around zero. As only the kinetic energy is forced, shouldn’t the
KE->PE conversion rate be nonzero a priori?
}
For Vincent...
\end{enumerate}
\subsection*{Minor comments}
......@@ -92,6 +116,7 @@
speeds, not scale separation as stated here.
}
\itemit{
(3) maybe it could be stated how these are derived from each other? Also,
the folklore in oceanography is that the internal wave energy flows downscale in
......@@ -99,6 +124,12 @@
that?
}
- oceans: forced waves (inertial waves, M2 and spontaneous generation from vortices) $\omega/N$ small.
- our results also transfers towards slow waves
- open question in ocean and in WWT theories
\itemit{
typo p4 hyper viscosity
}
......
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