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Hi everybody. I hope everybody is doing good.

My name is Jean Schuster, from Brazil.

I'm starting my studies in neural networks and machine learning, when I found a subject of interest in a paper named Hidden fluid mechanics: Learning velocity and pressure fields from flow visualizations.
In that papar, Dr. Raissi, Dr. Yazdani and Dr. Karniadakis addressed a fluid mechanics problem of flow visualization, like smoke or dye visualization for qualitative characterization of flow fields, "injecting" a passive escalar (say smoke) through a transport equation together with the Navier-Stokes equations, developing a framework that they called hidden fluid mechanics (HFM), a physics-informed deep-learning framework capable of encoding the Navier-Stokes equations into the neural networks while being agnostic to the geometry or the initial and boundary conditions.

That framework uses Nektar, that I suppose they had modified to insert the passive scalar transport equation, to run the CFD simulations for the example problems they demonstrate in the papar. It can be downloaded under a GNU general public license at: https://github.com/alirezayazdani1/HFM

After some days I managed to compile it and its dependencies in a 64bits Ubuntu 20.04.2 LTS machine. I attached a file called log_compiling.txt that  contains the terminal output during the compiling process.

Everything seems fine, but when I try to run, for example the classic problem of a flow over a cylinder that is included in the framework, I get an error saying: gen_bndry: Illegal B.C. function definition. I'm using the following command to run the example: ./nektar -V -chk -S -n4 ./RUN/Cylinder2D/cylinder2d.rea 2>&1 | tee log_run_cyl2d.txt

It returns:
jean@Prandtl:~/HFM/SourceCode$ ./nektar -V -chk -S -n4 ./RUN/Cylinder2D/cylinder2d.rea 2>&1 | tee log_run_cyl2d.txt
rcm bandwidth (u)   : 18080 [204031 (0)]
Input File          : /RUN/Cylinder2D/cylinder2d
Concat files       : 0
Re (U=1, L=1)       : 100
Time step           : 0.0008
Integration order   : 2
Number of modes     : 4
Number of elements  : 45856
Number of Families  : 45856
Equation type       : Navier-Stokes (convective)
Integration time    : 120.008, or 150010 steps
I/O time for saves  : 40, or 50000 steps [checkpoint]
NS Scheme Type      : Splitting scheme
Solver Type         : Direct RCM
gen_bndry: Illegal B.C. function definition

Follow attached the cylinder2d.rea file.

I would try to use some of the tutorials available here https://www.nektar.info/community/tutorials/ with the compiled code, but it returns me an error saying "The requested URL was not found on this server" in every link in the tutorials page.

I'm pretty sure that this is not exactly the right place for this question, but I don't know where else I could get help. So I hope I'm not bothering any of you.

Thanks in advance.

Best regards,
Jean.