Welcome, Guest
Username: Password: Remember me

TOPIC: Large-scale estuarine modelling of hydrodynamics: unstable results

Large-scale estuarine modelling of hydrodynamics: unstable results 4 years 1 month ago #36824

  • IPelckmans
  • IPelckmans's Avatar
Hi

I am modelling the hydrodynamics in the Gulf of Guayaquil, a large estuary. The seaward boundary is defined by a TPXO model. The upstream boundary by two boundaries with imposed discharges. For Bathymetry I am using a combination of the GEBCO database and data from local institutions.

When running the simulations, the model shows clear signs of numerical unstability close to the seaward boundary (see video attached).

I looked around on the forum and so far learned that the constant viscosity turbulence model with a not-too-small coefficient. While this already improved the stability compared to using a k-epsilon model, it is still not very stable. Time step is 3 sec and the stabilities are mostly appearing at the area where the spatial resolutions is the largest so I don't expect any Courant number violations.

Do you have any tips on further improving this?
I added the input cas file and resulting output video. Please let me know if I should any other files as well.

video: drive.google.com/file/d/1ruGsnIM19Ke4Ghj...uts/view?usp=sharing

Kind regards,
Ignace Pelckmans

File Attachment:

File Name: t2d_input_2020-09-28.cas
File Size: 2 KB
The administrator has disabled public write access.

Large-scale estuarine modelling of hydrodynamics: unstable results 4 years 1 month ago #36825

  • c.coulet
  • c.coulet's Avatar
  • OFFLINE
  • Moderator
  • Posts: 3722
  • Thank you received: 1031
Hi
I just had a look in the steering file
Why didn't you use the initial condition from TPXO?
Regards
Christophe
The administrator has disabled public write access.

Large-scale estuarine modelling of hydrodynamics: unstable results 4 years 1 month ago #36826

  • IPelckmans
  • IPelckmans's Avatar
Thank you for this suggestion.
The idea behind imposing another initial condition is that the TPXO won't be able to define the initial condition in the upstream parts of the estuary.
The administrator has disabled public write access.

Large-scale estuarine modelling of hydrodynamics: unstable results 4 years 1 month ago #36827

  • c.coulet
  • c.coulet's Avatar
  • OFFLINE
  • Moderator
  • Posts: 3722
  • Thank you received: 1031
I understand but is you initial condition consistent with TPXO on the marine part and particularly on the boundary?
Christophe
The administrator has disabled public write access.

Large-scale estuarine modelling of hydrodynamics: unstable results 4 years 1 month ago #36828

  • IPelckmans
  • IPelckmans's Avatar
There are some cm's difference but not more.
The administrator has disabled public write access.

Large-scale estuarine modelling of hydrodynamics: unstable results 4 years 1 month ago #36829

  • c.coulet
  • c.coulet's Avatar
  • OFFLINE
  • Moderator
  • Posts: 3722
  • Thank you received: 1031
Two complementary advises
  • Use Thomson boundary condition option
  • Maybe try to generate a marine bournady more perpendicular to the coast. Personnaly if I had to create a mesh for this area, I would tru to have part of circle between north and south limit
Christophe
The administrator has disabled public write access.
The following user(s) said Thank You: IPelckmans
Moderators: pham

The open TELEMAC-MASCARET template for Joomla!2.5, the HTML 4 version.