February 2021 - Nektar-users

Warning: Level 0 assertion violation Using Default variable expansion definition for field: u
by ztdepyahoo 21 Feb '21

21 Feb '21

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Instability of cylinder wake
by Samik Bhattacharya 21 Feb '21

21 Feb '21

******************* 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. ******************* Hi all, We are using Nektar for a problem related to the instability of cylinder wakes. We are facing some issues. It would be great to get some help from any users in the mailing lists who perform similar analyses using Nektar. Here are our questions: 1. Can we calculate the base flow in Nektar? Or should we just take a Reynolds number below the critical Reynolds number? 2. How do we import Openfoam mesh in Nektar? It will be very helpful to get some insight into these two issues. We will be glad to provide more information. Thanks, Samik

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Compresssible Navier-Stokes solver
by wasim sarwar 20 Feb '21

20 Feb '21

******************* 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, Good Morning, and wishing all of you very good day! I am trying to solve the problem of convergent-divergent nozzle with pressure at inlet and outlet. Does anyone have the idea how to setup the pressure inlet and pressure outlet boundary conditions in compressible Navier-Stokes solver. Also, give an idea of how-to setup the symmetry bc about x-axis. The input file is also attached herein for reference. Many thanks in advance Wasim Sarwar UPC, Barcelona

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FieldConvert -m addfld (detailed issue)
by Nikesh Yadav 17 Feb '21

17 Feb '21

******************* 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 have prepared files for comparison between 4.4 and 5.01 FieldConvert -m addfld feature. I am attaching the field (geom.fld) and mesh file (geom.xml). Using nektar++-4.4.1 i can successfully add for example FieldConvert -m addfld:fromfld=geom.fld:scale=1 geom.xml geom.fld geom2.fld output:- Writing: "geom2.fld" (0s, XML) Using nektar 5.01. i am getting an error FieldConvert -m addfld:fromfld=geom.fld:scale=1 geom.xml geom.fld geom2.fld Segmentation fault -- *Thanks and regardNikesh, Ph.D.* *Assistant at Aerodynamics Dept, * *MEiLWarsaw University of Technology, **Warsaw, Poland* *Contact: - **+48 22 234 7523* *Email-id: **nikeshspartan(a)gmail.com <nikeshspartan(a)gmail.com> / * *nyadav(a)meil.pw.edu.pl <nyadav(a)meil.pw.edu.pl>*

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Time dependent advection velocity evaluation in Nektar++
by Vidhi Zala 16 Feb '21

16 Feb '21

******************* 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. ******************* Hi all, I have been trying to get a time-dependent advection velocity case to work. I see that there is a variable m_velocity in UnsteadyAdvection.cpp. It gets initialized once using Evaluate() call. As I see it, there is no time variable in this initialization or an ability to evaluate m_velocity at each time-step. Any advice would be greatly appreciated :) Thanks V ,-~~-.___. ._. / | ' \ | |--------. Vidhi Zala ( ) 0 | | | School of Computing \_/-, ,----' | | | Scientific Computing and Imaging Institute ==== !_!-v---v--. University of Utah / \-'~; .--------. / __/~| ._-""|| | vidhi.zala(a)utah.edu =( _____|_|____||________| http://sci.utah.edu/people/vidhi.html

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help with 3D cases
by Alessandro Alberto de Lima 15 Feb '21

15 Feb '21

******************* 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. ******************* Hi. My name is Alessandro. I'm from Brazil end new user of nektar++. I work with professor Bruno Carmo and professor Julio Meneghini in the University of São Paulo. I'm trying to simulate 3d flow around the cylinder. I compiled nektar++ im my pc, a serial version, with no problems but the mpi version was not so well concluded. I run the 2D case of flow around the cylinder from the tutorial with no problems. Then I compiled nektar++ 5.0.1 with the optinos cmake -DNEKTAR_BUILD_DEMOS=ON -DNEKTAR_BUILD_TESTS=ON -DNEKTAR_USE_FFTW=ON -DNEKTAR_USE_MPI=ON .. I tried to run the 3D case described in the incns-taylor-green-vortex.pdf with the command: mpirun --hostfile myHost -np 8 IncNavierStokesSolver TGV64_mesh.xml TGV64_conditions.xml and mpirun -np 8 IncNavierStokesSolver TGV64_mesh.xml TGV64_conditions.xml I tried the two ways and both result in errors of mpi execution. Can you send me more specific examples of compilation, setup and run of 2.5D and 3D cases with periodic boundary conditions? Thanks for help. Alessandro

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how to monitor the heat flux or momentum flux along some boundary region.
by ztdepyahoo 14 Feb '21

14 Feb '21

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low mach precondition
by Cimpoeru, Ionut Andrei 14 Feb '21

14 Feb '21

******************* 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. ******************* Hi, Is there a low mach preconditioner implemented for the compressible code? Thanks a lot guys. Cheers, Andrei Not Subject to Export Control This information is provided by Rolls-Royce in good faith based upon the latest information available to it; no warranty or representation is given; no contractual or other binding commitment is implied. (c) 2021 Rolls-Royce The data contained in, or attached to, this e-mail, may contain confidential information. If you have received it in error you should notify the sender immediately by reply e-mail, delete the message from your system and contact +44 (0) 3301235850 (Security Operations Centre) if you need assistance. Please do not copy it for any purpose, or disclose its contents to any other person. An e-mail response to this address may be subject to interception or monitoring for operational reasons or for lawful business practices. (c) 2021 Rolls-Royce plc Registered office: Kings Place, 3rd Floor 90 York Way, London, N1 9FX Company number: 1003142. Registered in England

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cpu not running at 100%
by Cimpoeru, Ionut Andrei 14 Feb '21

14 Feb '21

******************* 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. ******************* Hi, I am running Nektar++ compressible code and I ssh in one of nodes. It looks like the cores are not all running at ~100% in the CPU column. Not sure if other people had this problem in the past but it looks like that this could affect the parallel efficiency. I don't have access to a profiler to check where the penalty comes from but I was thinking to check with the community. Cheers, Andrei [cid:image002.jpg@01D7005F.F339E5F0] Not Subject to Export Control This information is provided by Rolls-Royce in good faith based upon the latest information available to it; no warranty or representation is given; no contractual or other binding commitment is implied. (c) 2021 Rolls-Royce The data contained in, or attached to, this e-mail, may contain confidential information. If you have received it in error you should notify the sender immediately by reply e-mail, delete the message from your system and contact +44 (0) 3301235850 (Security Operations Centre) if you need assistance. Please do not copy it for any purpose, or disclose its contents to any other person. An e-mail response to this address may be subject to interception or monitoring for operational reasons or for lawful business practices. (c) 2021 Rolls-Royce plc Registered office: Kings Place, 3rd Floor 90 York Way, London, N1 9FX Company number: 1003142. Registered in England

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Re: [Nektar-users] 'Time-average fields' filter in Nektar++
by Gao, Ankang 13 Feb '21

13 Feb '21

Hi Zhaoyu, You are right, "the example above could only get the averaged flow of 0-10 tc and 0-20tc". Currently, there is no parameter to let the FilterAverageFields start after a certain number of time steps. You need to restart the simulation at 10c to do average between 10-20tc. Cheers Ankang ________________________________ From: Ankang Gao <gaoak(a)pku.edu.cn> Sent: 13 February 2021 14:00 To: Gao, Ankang <ankang.gao(a)imperial.ac.uk> Subject: Fw: [Nektar-users] 'Time-average fields' filter in Nektar++ -----原始邮件----- 发件人: "王昭予" <clemden(a)sjtu.edu.cn> 发送时间: 2021-02-13 19:00:16 (星期六) 收件人: nektar-users <nektar-users(a)imperial.ac.uk> 抄送: 主题: [Nektar-users] 'Time-average fields' filter in Nektar++ ******************* 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 confused with the 'Time-average fields' filter in Nektar++. If I carry on a simulation of a foil flow field in 20 characteristic time(tc) with 20000 time steps in total and I want to get the averaged flow field of 10-20 tc (not 0-20tc), how to set the filter options correctly? Here is an example: <FILTER TYPE="AverageFields"> <PARAM NAME="OutputFile">MyAverageField</PARAM> <PARAM NAME="OutputFrequency">10000</PARAM> <PARAM NAME="SampleFrequency"> 1 </PARAM> </FILTER> I think the example above could only get the averaged flow of 0-10 tc and 0-20tc. If I want to get the averaged flow of 10-20tc, should I suspend my simulation at 10tc（time step 10000）and restart it? I will be very grateful with your kind reply. Many thanks, Zhaoyu Wang Shanghai Jiao Tong University _______________________________________________ Nektar-users mailing list Nektar-users(a)imperial.ac.uk https://mailman.ic.ac.uk/mailman/listinfo/nektar-users

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