Adding a passive scalar transport with a Coordinate Transformation
******************* 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, When I run a 2.5D simulation with a coordinate transformation and an extra passive scalar transport, I get the following error: CG iterations made = 5001 using tolerance of 1e-09 (error = -nan, rhs_mag = 1) Fatal : Level 0 assertion violation Exceeded maximum number of iterations However, if I repeat the simulation without the passive scalar transport, it proceeds correctly. Has anyone else encountered the same problem? If so, would you be able to assist me in resolving it? Thank you in advance for youe help, Antonio.
Hi, Essentially the iterative solver does not converge. Probably in the passive scalar solve. I would guess that diffusivity of the passive scalar is significantly lower than viscosity. If this is the case, try to set it to be the same as viscosity (Schmidt or Prandtl number = 1). If this works, and solution progresses, you can try to play with the time step size while decreasing diffusivity to where you want it to be. This way you might get the acceptable time step size for your problem. Best regards, Stanisław Gepner, Ph.D. *Faculty of Power and Aeronautical Engineering* Nowowiejska 21/25 Str. 00-665 Warsaw, Poland phone +48 (22) 234 51 70 <https://www.pw.edu.pl/engpw> On 23.12.2024 14:07, ANTONIO MAZZARA wrote:
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Dear all,
When I run a 2.5D simulation with a coordinate transformation and an extra passive scalar transport, I get the following error: CG iterations made = 5001 using tolerance of 1e-09 (error = -nan, rhs_mag = 1) Fatal : Level 0 assertion violation Exceeded maximum number of iterations
However, if I repeat the simulation without the passive scalar transport, it proceeds correctly. Has anyone else encountered the same problem? If so, would you be able to assist me in resolving it? Thank you in advance for youe help,
Antonio.
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Hello Antonio, how are you? Usually, I get that error when the simulation diverges, so try to monitor the CFL to see if that is the case. If so, evaluate the possibility of reducing the time step. However, that could be the option of something wrong with the setup or the combination of methods is not implemented. I'm suspicious about that because the error would be completely different, I guess so... If you have solved the problem, please answer so it can be registered in the forum. Att, Daniel. Em seg., 23 de dez. de 2024 às 21:36, ANTONIO MAZZARA < ant.mazzara@studenti.unina.it> escreveu:
This email from ant.mazzara@studenti.unina.it 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,
When I run a 2.5D simulation with a coordinate transformation and an extra passive scalar transport, I get the following error: CG iterations made = 5001 using tolerance of 1e-09 (error = -nan, rhs_mag = 1) Fatal : Level 0 assertion violation Exceeded maximum number of iterations
However, if I repeat the simulation without the passive scalar transport, it proceeds correctly. Has anyone else encountered the same problem? If so, would you be able to assist me in resolving it? Thank you in advance for youe help,
Antonio. _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk https://mailman.ic.ac.uk/mailman/listinfo/nektar-users
participants (3)
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ANTONIO MAZZARA
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Daniel Garcia
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Stanislaw Gepner