Hi Wrik, If I understood correctly and pardon me if I am wrong, I think what you want is already implemented when Nekar++ was shipped with CWIPI. If you are using a CFD solver just create a coupler for that solver with CWIPI and you are done. If you are using some data from experiment all you need to do is create a dummy mesh and a buffer that holds some values of the source at those points and pass those to APESolver through CWIPI. The filtering of sources is then performed within the nektar framework, which in my experience is very robust. I have also used file based coupling and it also behaves in a similar way. However, I agree with you that the documentation is not that elaborate for these cases. On Tue, Nov 5, 2024 at 5:10 PM Wrik Mallik <Wrik.Mallik@glasgow.ac.uk> wrote:

Hi Nitish,

Thanks for participating in the conversation as a former user and providing technical feedback on generating Lamb vector. I am familiar with the CWIPI coupling. I have found the process to be completely reliant on OpenFOAM the way it has been developed. Furthermore, there are severe compatibility issues on what version of OpenFOAM, CWIPI or NEKTAR++ one is using.

My question to the Nektar++ developers (@nektar-users@imperial.ac.uk <nektar-users@imperial.ac.uk>) would be along same line as Fei Gao. Can we directly import lamb vector or filtered sources from other CFD solvers, or even experiment results, to the APE in Nektar? This would probably be reading some source file at various time instances. It seems such capabilities would be available in Nektar++ but I don’t see anything in the documentation or tutorials. Some advice in the regard would be very helpful.

Regards,

Wrik

*From: *nektar-users-bounces@imperial.ac.uk < nektar-users-bounces@imperial.ac.uk> on behalf of Nitish Arya < nitiesharya@gmail.com> *Date: *Tuesday, 5 November 2024 at 11:15 *To: *feigao2024 <feigao2024@126.com> *Cc: *nektar-users@imperial.ac.uk <nektar-users@imperial.ac.uk> *Subject: *Re: [Nektar-users] Question about Hybird CAA

Hi,

I worked on coupling Nektar++ and OpenFOAM a while back. To obtain lamb vector as a sound source, I first had a time averaged flow and then calculated the fluctuating lamb vector by subtracting the instantaneous lamb vector from the mean value. This value was then transferred to Nektar++ using CWIPI coupling. The process should be fairly similar if you are going for a file based coupling. You can refer to the following article for more information

Arya, Nitish, and Ashoke De. "Effect of vortex and entropy sources in sound generation for compressible cavity flow." *Physics of Fluids* 33.4 (2021).

cheers,

Nitish

On Tue, Nov 5, 2024 at 3:13 PM feigao2024 <feigao2024@126.com> wrote:

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Hello, everyone

I saw some posts regarding the CAA in Nektar, I have some questions. Also, I want to couple the Compressible solver and Acoustic solver.

First, how can I get the Lamb vector in Compressible solver?

Second, if I export the result average file from the thirdparty CFD solver, then how can I transform the result file to .fld or .pts?

Is there anything else I should be aware of about CAA in Nektar?

With best regards

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