March 2021 - Nektar-users - imperial.ac.uk

Turbulent channel flow test case
by Eli Frydman 07 Mar '21

07 Mar '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 tried to run the turbulent channel flow test case from the user guide (session file TurbChFl_3DH1D.xml) but i didn't get any turbulent flow. I used a body force in the u direction as explained and added also a perturbation in the spanwise direction and didn't get any transition. Regards, Eli

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simulation diverging during start-up
by Cimpoeru, Ionut Andrei 05 Mar '21

05 Mar '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 have a quad mesh generated in GMSH and then imported it in nectar using nekMesh. I am trying to run it using the incompressible solver 2D. I dropped to CFL considerably and the simulation is still diverging during startup at very low non dimensional time step 1e-8. Below are the expansion I am using using SVVcutoff=1 and Svvdivcoeff=0.5. I am trying to start the simulation using a low order as per my expansion and starting with a low Reynolds before I reach the actual conditions. The boundary conditions I am using are: Inflow>>>Dirichlet for Velocity and Von-Neumann for pressure Outlflow>>> Von-Neuman for velocity and Dirichlet for pressure using the Houtflow option Wall >>> using Dirichlet for velocity and von Neumann for pressure Are there any suggestions please? Thanks a lot and many thanks for any help. Cheers, Andrei <EXPANSIONS> <E COMPOSITE="C[100]" NUMMODES="3" FIELDS="u,v" TYPE="MODIFIED" /> <E COMPOSITE="C[100]" NUMMODES="2" FIELDS="p" TYPE="MODIFIEDQUADPLUS1" /> </EXPANSIONS> <SOLVERINFO> </SOLVERINFO> [cid:image002.jpg@01D711B6.D07C0DF0] 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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2D unstructured mesh
by Matt Duran 02 Mar '21

02 Mar '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, I currently have an issue with using 2D unstructured meshes in Nektar. The problem seems to be in using NekMesh to convert the .msh to .xml. I have attached the relevant files and an image of the .msh from gmsh and the mesh after being converted to .xml and then .vtu in Nektar. The converted xml appears to have a strange structure, I was wondering if I could get some guidance on how to avoid or fix this issue. Thanks for your time, Matt Duran Mechanical and Aerospace Engineering University of Central Florida [image: image.png] [image: image.png]

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