[Nek5000-users] Problem with Spatial Derivatives of field

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

Hello everyone,


Sorry for the delay, I was exploring all the possibilities that you have 
provided to me! I believe that the problem was solved.

Here is what I have done :


I have increased lx1, I have computed the components of the vorticity 
field using wgradm1. Then when I compute gradient of vorticity for every 
iteration, I diffuse it  over 5 time steps (with low values of dt) and 
this removes the problem at the interface of the elements!


Thank you for your help,


Best wishes,


Arnold



Le 06/03/2017 à 07:38, Arnold Wakim a écrit :
>
> 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
>
>
> ONERA - The French Aerospace Lab -Centre de Meudon
> 8, rue des Vertugadins - 92190 MEUDON
>
> Nous suivre sur : www.onera.fr <http://www.onera.fr/> | Twitter 
> <http://www.twitter.com/@onera_fr> | LinkedIn 
> <http://www.linkedin.com/company/onera> | Facebook 
> <http://www.facebook.fr/thefrenchaerospacelab>
>

-- 

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


ONERA - The French Aerospace Lab -Centre de Meudon
8, rue des Vertugadins - 92190 MEUDON

Nous suivre sur : www.onera.fr <http://www.onera.fr/> | Twitter 
<http://www.twitter.com/@onera_fr> | LinkedIn 
<http://www.linkedin.com/company/onera> | Facebook 
<http://www.facebook.fr/thefrenchaerospacelab>

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