Setting a maximum artificial viscosity value
******************* 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 everyone, I'm trying to run a complex transonic case in the CompressibleFlowSolver which keeps diverging at a specific point in flow time no matter which settings I put in, including using a few different meshes for that geometry. After playing around with an alternative solver I noticed that the stability of the simulation was highly dependent on the maximum artificial viscosity setting for the shock capture method. So I was wondering if there is an equivalent option in Nektar++? Ideally one which applies to the NonSmooth capture method but I can switch to Physical if necessary. Kind regards, Andrew
HI Andrew, We are tending to use the physical smoothing now, particularly with the implicit code. @Joao, Guglielmo can you have a chat with Andrew to see what might be going on? Cheers, Spencer. From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Andrew Barnes <A.Barnes2@lboro.ac.uk> Date: Friday, 3 March 2023 at 08:37 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Setting a maximum artificial viscosity value This email from A.Barnes2@lboro.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. Hello everyone, I'm trying to run a complex transonic case in the CompressibleFlowSolver which keeps diverging at a specific point in flow time no matter which settings I put in, including using a few different meshes for that geometry. After playing around with an alternative solver I noticed that the stability of the simulation was highly dependent on the maximum artificial viscosity setting for the shock capture method. So I was wondering if there is an equivalent option in Nektar++? Ideally one which applies to the NonSmooth capture method but I can switch to Physical if necessary. Kind regards, Andrew
Hi Spencer, Unfortunately I've been unable to get the implicit code to work despite trying on a few different workstations and HPC systems, with a few different compilation attempts, and it passing all of the tests in the ctest, so I've been using the explicit code with RK3 SSP. In terms of NonSmooth vs Physical, whilst Physical was working better in my early testing of the code on cylinders, NonSmooth is more stable with the current geometry and settings I've ended up on hence the preference. Kind regards, Andrew ________________________________ From: Sherwin, Spencer J <s.sherwin@imperial.ac.uk> Sent: 03 March 2023 09:43 To: Andrew Barnes <A.Barnes2@lboro.ac.uk>; nektar-users <nektar-users@imperial.ac.uk> Cc: Isler, Joao A <j.isler20@imperial.ac.uk>; Vivarelli, Guglielmo A <guglielmo.vivarelli12@imperial.ac.uk> Subject: Re: Setting a maximum artificial viscosity value ** THIS MESSAGE ORIGINATED OUTSIDE LOUGHBOROUGH UNIVERSITY ** ** Be wary of links or attachments, especially if the email is unsolicited or you don't recognise the sender's email address. ** HI Andrew, We are tending to use the physical smoothing now, particularly with the implicit code. @Joao, Guglielmo can you have a chat with Andrew to see what might be going on? Cheers, Spencer. From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Andrew Barnes <A.Barnes2@lboro.ac.uk> Date: Friday, 3 March 2023 at 08:37 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Setting a maximum artificial viscosity value This email from A.Barnes2@lboro.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. Hello everyone, I'm trying to run a complex transonic case in the CompressibleFlowSolver which keeps diverging at a specific point in flow time no matter which settings I put in, including using a few different meshes for that geometry. After playing around with an alternative solver I noticed that the stability of the simulation was highly dependent on the maximum artificial viscosity setting for the shock capture method. So I was wondering if there is an equivalent option in Nektar++? Ideally one which applies to the NonSmooth capture method but I can switch to Physical if necessary. Kind regards, Andrew
Dear Andrew, Thank you for your email. Could you give us a bit more info? A snap-shot of your case and RANS flow field along with the best Nektar++ input file could help us understand. Thanks, Guglielmo ________________________________ From: Sherwin, Spencer J <s.sherwin@imperial.ac.uk> Sent: 03 March 2023 09:43 To: Andrew Barnes <A.Barnes2@lboro.ac.uk>; nektar-users <nektar-users@imperial.ac.uk> Cc: Isler, Joao A <j.isler20@imperial.ac.uk>; Vivarelli, Guglielmo A <guglielmo.vivarelli12@imperial.ac.uk> Subject: Re: Setting a maximum artificial viscosity value HI Andrew, We are tending to use the physical smoothing now, particularly with the implicit code. @Joao, Guglielmo can you have a chat with Andrew to see what might be going on? Cheers, Spencer. From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Andrew Barnes <A.Barnes2@lboro.ac.uk> Date: Friday, 3 March 2023 at 08:37 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Setting a maximum artificial viscosity value This email from A.Barnes2@lboro.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. Hello everyone, I'm trying to run a complex transonic case in the CompressibleFlowSolver which keeps diverging at a specific point in flow time no matter which settings I put in, including using a few different meshes for that geometry. After playing around with an alternative solver I noticed that the stability of the simulation was highly dependent on the maximum artificial viscosity setting for the shock capture method. So I was wondering if there is an equivalent option in Nektar++? Ideally one which applies to the NonSmooth capture method but I can switch to Physical if necessary. Kind regards, Andrew
participants (3)
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Andrew Barnes
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Sherwin, Spencer J
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Vivarelli, Guglielmo A