________________________________________
From: nektar-users-bounces@imperial.ac.ukOn Behalf OfKilian Lackhove
Sent: October 26, 2018 3:58:07 AM (UTC-05:00) Eastern Time (US & Canada)
To: Amitvikram Dutta; nektar-users
Subject: Re: [Nektar-users] Questions regarding APE Solver
Hi Amitvikram,
1. Yes, only the lamb vector was used, so the RHS of the pressure
equation is zero.
2. It seems the userguide is out of date. In Nektar++ 4.4 the RHS are
specified using forcings (see the userguide). See e.g.
APE_2DPulseAdv_WeakDG_MODIFIED.xml example how this is set up in the xml
file. In short, you would have something like this:
<CONDITIONS>
...
<FUNCTION NAME="Source">
<E VAR="p" VALUE="0"/>
<E VAR="u" VALUE="define lamb vector here"/>
<E VAR="v" VALUE="define lamb vector here"/>
<E VAR="w" VALUE="define lamb vector here"/>
</FUNCTION>
</CONDITIONS>
<FORCING>
<FORCE TYPE="Field">
<FIELDFORCE> Source <FIELDFORCE/>
</FORCE>
</FORCING>
3. The next Nektar++ major release will ship a fieldfromstring module,
which should be able to compute the source terms without the pts detour.
Until then you can just use "FieldConvert foo.xml foo.chk bar.pts" to
obtain a pts file with the values at the quadrature points.
In general, Nektar++ 5.0.0 will contain many changes and improvements to
the acoustics solver, in particular with regard to hybdrid CAA
cosimulations, so you might want to give it a try once its released.
Cheers,
Kilian
Am 26.10.18 um 04:55 schrieb Amitvikram Dutta:
> Hi everyone,
>
> I'm trying to use the APE Solver in nektar++ to predict sound generation
> from a particular industrial flow. The work is similar in scope to that
> published in this recent paper :
> http://www.iccfd.org/iccfd10/papers/ICCFD10-248-Paper.pdf.
> I'm particularly interested in how to define the source term. If I
> understand the work correctly, in a flow dominated by coherent
> structures, the Lamb vector becomes the dominant source.
> This leads to my first question :
> 1.In the APE-4 formulation there are 2 coupled equations with seperate
> source terms - one for the pressure fluctuations and one for the
> velocity fluctuations. In the above paper when the authors state that
> only the lamb vector was considered as a source, was the source for the
> RHS of the pressure fluctuations set to zero?
> 2. If this was the case, how was this specified in the .xml file? The
> only example I have come across is in the user guide which shows
>
> <FUNCTION NAME="Source">
> <E VAR="S" VALUE="0" />
> </FUNCTION>
>
> If one wanted to specify the pressure and velocity source terms
> seperately how would one do it in the .xml file?
>
> 3. From older posts in the mailing list I have seen suggestions of a
> workflow where the .chk/.fld files are written into a .pts file and then
> post processed to obtain the acoustic source. Is there a relevant filter
> or an extension the FieldConvert module that allows direct conversion
> from a .fld/.chk to a .pts format? I know of the interppoints extension
> that allows export to a .dat format but not the .pts?
>
> Sorry for the lengthy post.
> Thanks in advance!
> --
>
> *Amitvikram Dutta*
>
> Graduate Research Assistant
>
> Fluid Mechanics Research Lab
>
> Multi-Physics Interaction Lab
>
> University of Waterloo
>
>
> _______________________________________________
> Nektar-users mailing list
> Nektar-users@imperial.ac.uk
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>
--
Dr.-Ing. Kilian Lackhove
Fachgebiet für Energie- und Kraftwerkstechnik
L1|08 114
Technische Universität Darmstadt
Otto-Berndt-Straße 3
D-64287 Darmstadt
Germany
Tel.: +49 6151 16 - 28915
Fax: +49 6151 16 - 6555
e-mail: lackhove@ekt.tu-darmstadt.de
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Amitvikram Dutta
Graduate Research Assistant
Fluid Mechanics Research Lab
Multi-Physics Interaction Lab
University of Waterloo