- Nektar-users - imperial.ac.uk

Imposing a constant flowrate question
by Kurt Sansom 03 Nov '21

03 Nov '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. ******************* It is not immediately clear to me if the flowrate forcing is limited to being applied to a single boundary? e.g. will it work for a channel flow with multiple inlets and/or outlets? or is it limited to a single boundary in the domain? Regards, ~Kurt -- Kurt Sansom

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How to do sensitivity analysis?
by shan xiangjun 03 Nov '21

03 Nov '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 want to use the Nektar++ to conduct structural sensitivity analysis on the flow problem. I can get direct and adjoint modes, but I don't know how to get the sensitivity of base flow modification and local feedback (as shown in figure). Can anyone help me? Looking forward to your reply! Best regards, Xiangjun Shan 从 Windows 版邮件<https://go.microsoft.com/fwlink/?LinkId=550986>发送

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mpirun error when using steady-state solver
by 李依然 31 Oct '21

31 Oct '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 trying to calculate a base flow with the steady-state solver using selective frequency damping. Recently, an error, shown in the picture below, was given when I tried to run in parallel the IncNavierStokesSolver for my new mesh-refined case using mpirun -np: [cid:53ae808d-8f8c-4062-9c1e-374f9c477a1c] However, this error has never occurred before when: 1.using serial running for the same session file/ setting of this mesh-refined case; 2.using parallel running for other cases so far, which are all with much coarser meshes; So I want to know what triggered this kind of problem and how to deal with it. Thanks in advance for the help. Best regards, Mona.

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Nektar++ Workshop 13th-15th December 2021
by Chris Cantwell 15 Oct '21

15 Oct '21

Dear all, We are planning to hold the next Nektar++ workshop on the 13th-15th December 2021 at Imperial College London. So please save the date! The format will be hybrid and we plan to accommodate a fixed number of in-person attendees as well as allowing others to participate remotely. The main sessions of talks will likely be in the afternoon (UK time) to allow as many of you to join as possible. We are still finalising the details, but will put more information online soon, including how to register. We are looking forward to seeing as many of you as possible in London and being able to catch-up with our community again! Kind regards, Chris -- Chris Cantwell Senior Lecturer in Aeronautics 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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Noise Force Specification
by Marc Goldbach 13 Oct '21

13 Oct '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, What is the proper way to specify a noise force and a body force at the same time? I am new to Nektar++, and am attempting to run a simulation of turbulent channel flow using a body force to drive the bulk flow, and a noise force to generate some initial "turbulent-like" fluctuations of the velocity field. However, when I setup the case based on the details found in the user guide (Forcing (nektar.info) <https://doc.nektar.info/userguide/latest/user-guidese10.html#x16-810003.5> ), the resulting flow field doesn't show any "noise component". Is there some error in my settings for this case?: <NEKTAR> <CONDITIONS> ... <FUNCTION NAME="BodyForce"> <E VAR="u" VALUE="-(Re*Kinvis/H)^2/H" /> <E VAR="v" VALUE="0" /> <E VAR="w" VALUE="0" /> </FUNCTION> </CONDITIONS> <FORCING> <FORCE TYPE="Body"> <BODYFORCE> BodyForce </BODYFORCE> </FORCE> <FORCE TYPE="Noise"> <WHITENOISE> 0.5 </WHITENOISE> <UPDATEFREQ> 10 </UPDATEFREQ> </FORCE> </FORCING> </NEKTAR> Regards, *Marc Goldbach* PhD Student, Department of Mechanical Engineering University of North Carolina at Charlotte

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variable coeffient in Helmholtz solver
by mohammadreza rouhanian 29 Sep '21

29 Sep '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 want to solve a two-phase flow with Nektar++. The governing equations lead to div(viscosity(grad) - factor)u=RHS that should solve with Helmholtz solver in the velocity correction scheme. As the flow is two-phase the viscosity varied across the domain. To solve the above equation, I set eVarCoeff D00=D11=D22=viscosity, but it doesn't work. Would you say how can I set the above equation in helmsolve? best regards, Rouhanian

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FieldConvert
by Alessandro Alberto de Lima 21 Sep '21

21 Sep '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'm trying to convert a field to some specific points. I tried to use: mpirun -np 32 FieldConvert-rg -m interppoints:fromxml=1cylQ3D_msh2.xml:fromfld=1cylQ3D_msh2.fld:box=400,200,300,-1.0,3.0,-1.0,1.0,0.001,3.0 1cylQ3D_msh2_2059.dat and i get a "Segmentation fault" as result. Then I tried as a simple test: FieldConvert -m interppoints:fromxml=1cylQ3D_msh2.xml:fromfld=1cylQ3D_msh2.fld:topts=file.csv file2.dat The file.csv: # x, y, z 5.0,-2.0,1.0 7.5,2.0,1.0 8.0,5.0,1.0 And had the same "Segmentation fault" as result. Before all of that, i was converting my fields to paraview and then converting to csv files. I'm spanding to much time. There is a method to generate a csv field direct from nektar? Thank you for your support. Alessandro

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Acoustics of Laminar Flow Cylinder
by Paul Liu 21 Sep '21

21 Sep '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 Everyone, I am a current masters student trying to work on some acoustics. I was wondering if anyone has any experience with trying to calculate the acoustic perturbation pressure of a simple stationary cylinder in laminar flow. Specifically, I am trying to use the -dp/dt (time derivative of pressure) from a DNS (direct numerical simulation) of the flow solution for the laminar flow of the cylinder (Re=200). This term seems quite large up to 200+ in magnitude which perplexes me. I am trying to insert -dp/dt as a source in the pressure/energy equation. If anyone has any tips or thoughts please let me know. Thank you all so much. *YiLin Liu * *403-397-3457* *liuyilin.liu(a)gmail.com <liuyilin.liu(a)gmail.com>* MASc Student at CML <https://cml.mech.ubc.ca/> UBC

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Elastodynamic solver
by Lozano Duarte, Daniel Hernando 01 Sep '21

01 Sep '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, Receive a warm greeting from Berlin, I am a PhD student and currently, I am working in elastodynamic models for the study of guided waves propagation. My framework is a semi-analytical method called the Scaled Boundary Finite Element Method. However, I have been exploring other possibilities and ended up finding Nektar++. So as you might notice I am new with Nektar, but there is no solver for the equations of elastodynamics. I would like to know if some of you have some experience with this, I'd really appreciate your support. I thank you in advance! Looking forward to hearing from you soon! Regards, Daniel. Bundesanstalt für Materialforschung und -prüfung (BAM) Daniel Hernando Lozano Duarte 8.4 Division/Section (Acoustic and Electromagnetic Methods) Unter den Eichen 87 12205 Berlin GERMANY P: + 49 30 8104-4538 + 39 3382621636 Daniel-Hernando.Lozano-Duarte(a)bam.de<mailto:Daniel-Hernando.Lozano-Duarte@bam.de> www.bam.de<http://www.bam.de/> _______________________________________________________ Die BAM ist eine Bundesoberbehörde im Geschäftsbereich des Bundesministeriums für Wissenschaft und Energie.

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Senior RSE position at Imperial in the Department of Aeronautics
by Sherwin, Spencer J 03 Aug '21

03 Aug '21

Dear all, Please find attached an Research Software Engineering opportunity which might be of interest. This position will in part be related to supporting Nektar++ Details can be found under: https://www.imperial.ac.uk/jobs/description/ENG01820/senior-research-softwa… Best regards, Spencer. Spencer Sherwin FREng, FRAeS Head of Aerodynamics Section, Director of Research Computing Service, Professor of Computational Fluid Mechanics, Department of Aeronautics, South Kensington Campus, Imperial College London, SW7 2AZ, UK Phone: +44 (0)20 7594 5052 http://www.imperial.ac.uk/people/s.sherwin/

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