******************* 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 Nektar users, I am running some 3D incompressible simulations. The problem I faced is that the software gives me identical CFL numbers for all time steps. Also, the simulation results do not change with time, which is not correct. The flow is turbulent and the Reynolds number is 10000. Steps: 20 Time: 2e-06 CPU Time: 8.2572s CFL: 0.338963 (in elmt 105130) Steps: 30 Time: 3e-06 CPU Time: 7.98256s CFL: 0.338963 (in elmt 105130) Steps: 40 Time: 4e-06 CPU Time: 7.94238s CFL: 0.338963 (in elmt 105130) Steps: 50 Time: 5e-06 CPU Time: 7.99028s CFL: 0.338963 (in elmt 105130) Steps: 60 Time: 6e-06 CPU Time: 8.02182s CFL: 0.338963 (in elmt 105130) Steps: 70 Time: 7e-06 CPU Time: 8.03556s Have you ever faced this issue? and any solutions for that? Many thanks. Best regards Mahdi This message is intended solely for the addressee and may contain confidential and/or legally privileged information. Any use, disclosure or reproduction without the sender's explicit consent is unauthorised and may be unlawful. If you have received this message in error, please notify Northumbria University immediately and permanently delete it. Any views or opinions expressed in this message are solely those of the author and do not necessarily represent those of the University. Northumbria University email is provided by Microsoft Office365 and is hosted within the EEA, although some information may be replicated globally for backup purposes. The University cannot guarantee that this message or any attachment is virus free or has not been intercepted and/or amended.
Dear Mahdi, Thank you for your email. Could please give us a bit more info regarding the actual problem? I.e. setup file and what sort of geometry you are using. Thanks, Guglielmo ________________________________ From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Mahdi Erfanian Nakhchi <mahdi.nakhchi@northumbria.ac.uk> Sent: 19 November 2022 12:46 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Constant CFL number This email from mahdi.nakhchi@northumbria.ac.uk 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 Nektar users, I am running some 3D incompressible simulations. The problem I faced is that the software gives me identical CFL numbers for all time steps. Also, the simulation results do not change with time, which is not correct. The flow is turbulent and the Reynolds number is 10000. Steps: 20 Time: 2e-06 CPU Time: 8.2572s CFL: 0.338963 (in elmt 105130) Steps: 30 Time: 3e-06 CPU Time: 7.98256s CFL: 0.338963 (in elmt 105130) Steps: 40 Time: 4e-06 CPU Time: 7.94238s CFL: 0.338963 (in elmt 105130) Steps: 50 Time: 5e-06 CPU Time: 7.99028s CFL: 0.338963 (in elmt 105130) Steps: 60 Time: 6e-06 CPU Time: 8.02182s CFL: 0.338963 (in elmt 105130) Steps: 70 Time: 7e-06 CPU Time: 8.03556s Have you ever faced this issue? and any solutions for that? Many thanks. Best regards Mahdi This message is intended solely for the addressee and may contain confidential and/or legally privileged information. Any use, disclosure or reproduction without the sender’s explicit consent is unauthorised and may be unlawful. If you have received this message in error, please notify Northumbria University immediately and permanently delete it. Any views or opinions expressed in this message are solely those of the author and do not necessarily represent those of the University. Northumbria University email is provided by Microsoft Office365 and is hosted within the EEA, although some information may be replicated globally for backup purposes. The University cannot guarantee that this message or any attachment is virus free or has not been intercepted and/or amended.
Dear Guglielmo, Thank you for your response. It is turbulent flow around rotating quadcopter blades using MRF. The blades rotate with Omega=20 around pivot point (0,0,0). I noticed that when I use Omega=3 or smaller, the flow will be transient and CFL changes with time. When I increase it to larger numbers like Omega=20, the flow will not change with time and the CFL number remains identical. And the solver results look steady. <FUNCTION NAME="VelMRF"> <E VAR="u" VALUE="0.0" /> <E VAR="v" VALUE="0" /> <E VAR="w" VALUE="0" /> </FUNCTION> <FUNCTION NAME="OmegaMRF"> <E VAR="Omega_z" VALUE="-20"/> </FUNCTION> </CONDITIONS> <FORCING> <FORCE TYPE="MovingReferenceFrame"> <LinearVelocity> VelMRF </LinearVelocity> <AngularVelocity> OmegaMRF </AngularVelocity> <PivotPoint> 0.0 0.0 0.0 </PivotPoint> </FORCE> </FORCING> Best regards Mahdi ________________________________ From: Vivarelli, Guglielmo A <guglielmo.vivarelli12@imperial.ac.uk> Sent: 19 November 2022 15:33 To: Mahdi Erfanian Nakhchi <mahdi.nakhchi@northumbria.ac.uk>; nektar-users <nektar-users@imperial.ac.uk> Subject: Re: Constant CFL number CAUTION: This email originated from outside of the University. Do not click links or open attachments unless you recognise the sender and know the content is safe. Dear Mahdi, Thank you for your email. Could please give us a bit more info regarding the actual problem? I.e. setup file and what sort of geometry you are using. Thanks, Guglielmo ________________________________ From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Mahdi Erfanian Nakhchi <mahdi.nakhchi@northumbria.ac.uk> Sent: 19 November 2022 12:46 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Constant CFL number This email from mahdi.nakhchi@northumbria.ac.uk 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://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fspam.ic.ac.uk%2FSpamConsole%2FSenders.aspx&data=05%7C01%7Cmahdi.nakhchi%40northumbria.ac.uk%7Ccc65d35026244a17278f08daca4377fd%7Ce757cfdd1f354457af8f7c9c6b1437e3%7C0%7C0%7C638044688372727340%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=naDVYFP8ZqOP4gtC3cTh92CCLnYDTjfaBH5dxyI9Uto%3D&reserved=0> to disable email stamping for this address. Dear Nektar users, I am running some 3D incompressible simulations. The problem I faced is that the software gives me identical CFL numbers for all time steps. Also, the simulation results do not change with time, which is not correct. The flow is turbulent and the Reynolds number is 10000. Steps: 20 Time: 2e-06 CPU Time: 8.2572s CFL: 0.338963 (in elmt 105130) Steps: 30 Time: 3e-06 CPU Time: 7.98256s CFL: 0.338963 (in elmt 105130) Steps: 40 Time: 4e-06 CPU Time: 7.94238s CFL: 0.338963 (in elmt 105130) Steps: 50 Time: 5e-06 CPU Time: 7.99028s CFL: 0.338963 (in elmt 105130) Steps: 60 Time: 6e-06 CPU Time: 8.02182s CFL: 0.338963 (in elmt 105130) Steps: 70 Time: 7e-06 CPU Time: 8.03556s Have you ever faced this issue? and any solutions for that? Many thanks. Best regards Mahdi This message is intended solely for the addressee and may contain confidential and/or legally privileged information. Any use, disclosure or reproduction without the sender’s explicit consent is unauthorised and may be unlawful. If you have received this message in error, please notify Northumbria University immediately and permanently delete it. Any views or opinions expressed in this message are solely those of the author and do not necessarily represent those of the University. Northumbria University email is provided by Microsoft Office365 and is hosted within the EEA, although some information may be replicated globally for backup purposes. The University cannot guarantee that this message or any attachment is virus free or has not been intercepted and/or amended. This message is intended solely for the addressee and may contain confidential and/or legally privileged information. Any use, disclosure or reproduction without the sender’s explicit consent is unauthorised and may be unlawful. If you have received this message in error, please notify Northumbria University immediately and permanently delete it. Any views or opinions expressed in this message are solely those of the author and do not necessarily represent those of the University. Northumbria University email is provided by Microsoft Office365 and is hosted within the EEA, although some information may be replicated globally for backup purposes. The University cannot guarantee that this message or any attachment is virus free or has not been intercepted and/or amended.
participants (2)
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Mahdi Erfanian Nakhchi
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Vivarelli, Guglielmo A