January 2025 - Nektar-users

Nektar++ Workshop 2025
by Chris Cantwell 21 May '25

21 May '25

Dear all, This year's Nektar++ Workshop will be held on the 24th-26th June 2025 at Imperial College London. We are pleased to announce that Tzanio Kolev (leader of the MFEM project) has agreed to give a keynote lecture at the workshop. More information will be made available via the website soon, including how to register. As with recent years, the event is primarily an in-person meeting, but we will aim to allow the talks to be viewed remotely for those unable to travel. Kind regards, Chris -- Chris Cantwell Reader in Computational Engineering Director of Postgraduate Studies (PhD) Department of Aeronautics Imperial College London South Kensington Campus London SW7 2AZ Tel: +44 (0)20 759 45050 Email: c.cantwell(a)imperial.ac.uk www.imperial.ac.uk/people/c.cantwell

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Compressible Navier-Stokes Homogenous 1D
by Zhicheng Wang 25 Jan '25

25 Jan '25

******************* This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address. ******************* Dear Nektar++ Users and Developers, I’m running the compressible flow past a cylinder using the Nektar++ compressible flow solver. So far the implicit time stepping method works well both in 2D and 3D. However, when I try to run 3DHomogenous1D NavierStokesImplicitCFE solver, it gives me error says v_GetLocTraceToTraceMap not coded. I wonder if I have not set the session file correctly or this implicit 1D homogenous solver has not been implemented yet ? Below is solver information, in case I have used the wrong parameters. <SOLVERINFO> . </SOLVERINFO> Best Regards, Zhicheng Wang

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Problem in using "NekPy" instead of "FieldConvert" utility
by Sina Asadi 22 Jan '25

22 Jan '25

******************* This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address. ******************* Dear all, I'm using "FieldConvert" utility (Shell command) multiple times in a python code and it is working well. Now I want to use NekPy modules instead to decrease running time of "FieldConvert" execution. But I ran into a problem and I can't solve it. I will give you a simple example: In a python code, when I run the following two similar "FiledConvert" shell commands, I expect to get two identical output and I get it correctly: !FieldConvert -f -m gradient mesh.xml fields.fld output1.fld !FieldConvert -f -m gradient mesh.xml fields.fld output2.fld And in NekPy when I run the equivalent codes twice in my .py code: from NekPy.FieldUtils import * import sys field = Field(sys.argv, force_output=True) InputModule.Create("xml", field, "mesh.xml").Run() InputModule.Create("fld", field, "fields.fld").Run() ProcessModule.Create("gradient", field).Run() OutputModule.Create("fld", field, output1).Run() InputModule.Create("xml", field, "mesh.xml").Run() InputModule.Create("fld", field, "fields.fld").Run() ProcessModule.Create("gradient", field).Run() OutputModule.Create("fld", field, output2).Run() I get two different outputs, output1.fld and output2.fld It seems that both "gradient" ProcessModule are used in the second output. I can't find a way to prevent the first "gradient" module from being used in the second output. Surely this problem have an easy solution. I would be grateful if you could help me solve this problem. Sina.

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Gaussian Noise Generator in Quasi-3D Approach
by Selman BAYSAL 03 Jan '25

03 Jan '25

******************* This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address. ******************* Dear All,I am working to gain a better understanding of modeling turbulent flows. Some of the topics I am interested are if defining “small initial perturbations (noise)” is necessary in turbulent flow modeling, and how the noise affects the stability of the model. Therefore, I have conducted a literature review, but I have only been able to find a few studies* regarding the Gaussian Noise generator. It would be very helpful if I could review a few more studies on introducing noise particularly into Quasi-3D models. Are there any academic papers or tutorials you could recommend?Any recommendations would be greatly appreciated!Best regards,Selman BaysalR. A. in HydraulicsDept. of Civil Eng'gÇanakkale Onsekiz Mart University--ITU Civil Eng., BSc.ITU Coastal Sci. &amp; Eng., MSc.*Moxey et al. (2020) and &nbsp;Nektar++ tutorial

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Re: [Nektar-users] Adding a passive scalar transport with a Coordinate Transformation
by Daniel Garcia 02 Jan '25

02 Jan '25

I can't be sure as I've never adopted some methods that you are using. Once, I heard that a colleague had issues with mapping + homogeneous expansion, after all he ended up using a 3D mesh. He did not use a passive scalar, but his problems were related to the results, I'm not sure what exactly. Anyway, are you sure about your body force implementation? Are you aware it's being defined for the whole domain and every time step? Perhaps, you should test without the body force and/or for a specific region and not state the same values of w for T. Also, if doable, I suggest trying with a 3D mesh. Beyond that, I would not know what to suggest, sorry. Em qui., 2 de jan. de 2025 às 10:33, Antonio Mazzara < ant.mazzara(a)studenti.unina.it> escreveu: > Hi Daniel, > > Thank you very much for your response to my previous message. I greatly > appreciate the time you took to provide me with potential solutions. > > Unfortunately, I regret to inform you that despite following your > suggestions, the issue I originally reported still persists. I tried > different combinations of methods and even reduced the timestep. > > To assist you in further investigating the problem, I have attached part > of my configuration file for your review. I hope it can help identify any > potential inconsistencies or errors that might be contributing to the issue. > > Please let me know if there’s any additional information I can provide to > assist you. I remain at your disposal for further clarification or testing > if needed. > > Thank you again for your support and patience. > > Looking forward to your reply. > > Best regards, > Antonio > > Il 27/12/2024 18:20, Daniel Garcia ha scritto: > > Hello Antonio, how are you? > > Usually, I get that error when the simulation diverges, so try to monitor > the CFL to see if that is the case. If so, evaluate the possibility of > reducing the time step. > However, that could be the option of something wrong with the setup or the > combination of methods is not implemented. I'm suspicious about that > because the error would be completely different, I guess so... > > If you have solved the problem, please answer so it can be registered in > the forum. > > Att, > Daniel. > > > > > > > > Em seg., 23 de dez. de 2024 às 21:36, ANTONIO MAZZARA < > ant.mazzara(a)studenti.unina.it> escreveu: > >> This email from ant.mazzara(a)studenti.unina.it originates from outside >> Imperial. Do not click on links and attachments unless you recognise the >> sender. If you trust the sender, add them to your safe senders list >> <https://spam.ic.ac.uk/SpamConsole/Senders.aspx> to disable email >> stamping for this address. >> >> >> Dear all, >> >> When I run a 2.5D simulation with a coordinate transformation and an >> extra passive scalar transport, I get the following error: >> CG iterations made = 5001 using tolerance of 1e-09 (error = -nan, rhs_mag >> = 1) >> Fatal : Level 0 assertion violation >> Exceeded maximum number of iterations >> >> However, if I repeat the simulation without the passive scalar transport, >> it proceeds correctly. >> Has anyone else encountered the same problem? If so, would you be able to >> assist me in resolving it? >> Thank you in advance for youe help, >> >> Antonio. >> _______________________________________________ >> Nektar-users mailing list >> Nektar-users(a)imperial.ac.uk >> https://mailman.ic.ac.uk/mailman/listinfo/nektar-users >> >

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