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 It seems the userguide is out of date.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

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