February 2021 - Nektar-users

compressible flow solver with quasi3d
by Cimpoeru, Ionut Andrei 13 Feb '21

13 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 guys, I've just started using with Naktar. Has anyone tried to use the compressible flow solver with quasi3d? Thanks, 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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'Time-average fields' filter in Nektar++
by 王昭予 13 Feb '21

13 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 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

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Help with Installation
by Samik Bhattacharya 09 Feb '21

09 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 trying to install Nektar in Ubuntu following the instructions provided in the PDF ( - user-guide-5.0.1.pdf <http://www.nektar.info/downloads/file/user-guide-pdf-5/> But we are having some issues while trying to install. The issues are related to installing third-party software. Although we installed some of the packages (LAPACK, ARPACK) separately, we are still getting some error messages. We are also getting errors related to VTK which we figured out to be related to open cascade. Anyway, the main problem is that we are not familiar with Linux systems. Hence, it would be very helpful if anyone can help us with the installation. We can give our TeamViewer ID and password so that anyone willing to help us can access our system. This may be an awkward request, but this will save us a lot of time. Samik

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specify different solution points
by Cimpoeru, Ionut Andrei 09 Feb '21

09 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 guys, In the expression below, as I understood correctly, you can change the order of the polynomial. How can I can change the distribution of the nodes inside the element i.e. Gauss Lobatto, Legendre Gauss Lobatto or Equidistant Spacing? Thanks a lot for your help guys. <EXPANSIONS> <E COMPOSITE="C[100]" NUMMODES="3" FIELDS="rho,rhou,rhov,rhow,E" TYPE="MODIFIED" /> </EXPANSIONS? 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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Post-processing of Nektar++ results
by Yong Wang 08 Feb '21

08 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. ******************* Hello Nektar++ Users, I am curious about how to best post-process simulated high-order results from Nektar++. I tried using Paraview to generate the contour plot of the vorticity field, but it seems quite blurry, which is due to, in my understanding, that Paraview uses linear interpolation to interpret the high-order results. I am currently using Matlab to generate the contour plot with high-order interpolations from a for-loop of the element-wise results, but it requires a lot of tweaking, calculation time, and data extraction. Do you have some advice on the post-processing of high-order results from Nektar++? Much appreciated. Thanks, Yong Wang Ph.D. Candidate National Wind Institue Texas Tech University Lubbock, TX, US

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A simple question about the "restart file" (*.rst)
by Selman Baysal 07 Feb '21

07 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’m a Ph.D. student in Istanbul Technical University and trying to learn more about Nektar++ to use it in my future doctorate thesis. I have done all the tutorials that given to users by Nektar++ (in official website) but confused about creating and/or obtaining a restart file (*.rst). For example, in Flow Stability – Channel tutorial, a restart file (Channel-VCS.rst in the Stability folder) was provided to users but i could not understand how it can be created or obtained for other simulations. I read its definition and understand the differences between Channel-VCS.bse and Channel-VCS.rst (the latter one contains eingenvalues/eingenmodes of the system). I would be very grateful if you could help me understand. Sincerely yours. Selman Baysal R. A. in Hydraulics Dept. of Civil Eng’g Çanakkale Onsekiz Mart University <> — ITU Civil Eng., BSc. ITU Coastal Sci. & Eng., MSc. Gsm: +905436180777 —

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Robin Boundary Condition
by Silvia Ceccacci (HDR) 05 Feb '21

05 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 would like to have some clarification on how the Robin Boundary Conditions work on Nektar++. In particular, I would like to know how the normal derivative is calculated on a curved surface, where the normal to the surface is in the radial direction. Please find attached notes.pdf, where I try to explain myself a bit better. I hope my question it is clear enough. Thank you for your help. Kind regards, Silvia

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A problem for installing Nektar++
by 朝黎明 03 Feb '21

03 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 am a beginner of Nektar++. I prepared to install the Nektar++ at Ubuntu 18.04. However, some problem have occurred when I installed the source package. When running the "ccmake ..", a Cmake error happened where it said "cannot build scotch". Actually, I have install the scotch lib. I have attached the screenshot, would anyone give me any suggestions? With best wishes! Li-Ming

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