[Nek5000-users] Problem with Spatial Derivatives of field

[nek5000-users at lists.mcs.anl.gov]

Good Morning,


Sorry for taking so long to answer. First I wanted to say that I really 
appreciate all of your help!

I am currently trying all these methods :

- as suggested by Paul Fischer, increasing LX1 and low pass filtering.

- and smoothing the derivatives. I will keep you posted on the results.


What I am trying to do is studying optimal perturbations using a 
DIRECT-ADJOINT approach so as to optimize quantities.
However, when I am writing the equations, I have no choice but taking 
the spatial derivatives of vorticity.

Computing the derivatives is made for every DIRECT Numerical Simulation 
of the perturbations. Then I call the ADJOINT solver of Nek5000

In order to converge towards optimum this may take several iterations 
let's say N ( roughly N=10 however since the gradients are not well 
resolved then I cannot tell whether I'm converged or not). The point is 
that I am computing vorticity, then computing the gradients of the same 
initial field, and this, N times. This leads to the problem I am facing.

Hope that helps understanding the issue. If you have more questions, 
please do not hesitate to ask.


Best wishes,


Arnold





Le 03/03/2017 à 21:33, nek5000-users at lists.mcs.anl.gov a écrit :
> call col2(dTdx,bm1,n)                    ! collocate with the mass matrix
> call dssum(dTdx,nx1,ny1,nz1)       ! smooth
> call col2(dTdx,bintm1,n)                ! collocate with the inverse 
> mass matrix

-- 

*Arnold Wakim*
Doctorant,
Département d´Aérodynamique Fondamentale et Expérimentale
Tél: +33 1 46 23 51 83


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