June 2020 - Nektar-users - imperial.ac.uk

TimeIntegrationMethod in 3D homogeneous case
by Moto Light 14 Jun '20

14 Jun '20

******************* 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 wish all of you are fine these days, I am running a 3D homogeneous case for a square cylinder, when I run the case at high Reynolds 2000 it keeps crashing, I tried *"SpectralVanishingViscosity"* it is working but it is filtering my field, what about using a different time integration method *"BDFImplicitOrder2" *instead of using *"IMEXOrder2"*, I think the two of them are 2nd order but using Implicit instead of Implicit explicit will not crash, but also I will keep CFL under 1 to be sure it is fine, even with this method i can go for higher CFL, my Reynolds is 2000 turbulent flow. Regards, Reda UPC Barcelona +34 632 675 853

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Rescaling velocity inlet conditions read from .fld files
by Vishal Saini 14 Jun '20

14 Jun '20

******************* 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 a little query regarding reading time varying turbulent BC from .fld files in IncNSSolver. With Dave 's helping hand I am now able to read in the .fld BC files. However, to reduce pressure fluctuations at the inlet, I'd like to rescale the inlet flow-rate to a required flow-rate for every time-step. This would typically include the following steps: 1. Find area of the inlet boundary 2. Take dot product of area normal and velocity vectors 3. Multiply the velocity vector with a correction factor (Q_ideal/Q_calculated) In this regard, the function VelocityCorrectionScheme::MeasureFlowrate looks interesting. However, I have little idea where to start with. Could someone drop any hints on where can I start with this in the code? BR, Vishal

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iLES/uDNS
by wasim sarwar 14 Jun '20

14 Jun '20

******************* 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 again Here, I share the settings that I used <SOLVERINFO> </SOLVERINFO> cheers

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ILES/UDNS
by wasim sarwar 14 Jun '20

14 Jun '20

******************* 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 wish all of you are fine and safe. I am wondering how ILES/uDNS could be implementated in the IncompressibleNavierStokes solver. If by any chance, anyone has come across this problem, please share the settings. I tried different settings of SVV and Dealising in 3DHomo1D case to stabilize the computations but didn't work for me. Thanking in advance, Wasim Sarwar PhD student, UPC, Barcelona

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loading data of velocity components from a file(*.fld) or expression into user-defined arrays in Nektar++
by 王昭予 01 Jun '20

01 Jun '20

******************* 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 load data of velocity components(u,v,w) from a file(*.fld) or expression into a user-defined array just like that in boundary conditions: <D VAR="u" USERDEFINEDTYPE="TimeDependent" VALUE="sin(PI*(x-t))" /> <REGION REF="1"> <D VAR="u" USERDEFINEDTYPE="TimeDependent" VALUE="sin(PI*(x-t))" FILE="bcsfromfiles_u_1.bc" /> </REGION> I wonder how it works. My purpose is to load the data into some arrays defined by myself like U[i], V[i], W[i] with the mesh data. Then I can use the data on each mesh point for further computation. Could you please tell me how to realize it with codes in Nektar++? I have check the codes in Explist.cpp, SessionReader.cpp, Conditions.cpp and IncNavierStokes.cpp but still have no idea. Many thanks, Zhaoyu Wang Shanghai Jiao Tong University

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