Boundary conditions in a marine zone with very high depths

EFDC_Explorer
1

Hello everyone.I’m trying to model hydrodynamics in a marine zone with very high depths (see Depth image) and highly stratified temperature.As initial conditions of temperature and salinity I am using field measurements from the surface to the bottom with seven layers. The temperature varies from 8 °C at the bottom to 22 °C at the surface. Salinity does not vary significantly. I’m using a complete atmospheric series and wind velocities as atmospheric forcing.I have three open boundaries (East, North and South) in which I am using seven (7) tidal harmonic constituents for that specific zone.The model is apparently stable, but as the simulation progresses, the velocities increase continuously, but only at the boundaries (see image “Magnitude”), reaching very high velocities that are evidently not normal. As I said, this only occurs at the boundary, the rest of the study domain shows velocities and behavior reasonable.I did some tests with fairly low time step, dynamic time step and the problem is the same.I’ll appreciate you tell me how I can correct this problem or explain what could be happening.Thanks! Attached files

2

Have you deactivated the corner cells where the open boundaries meet as outlined here? https://eemodelingsystem.atlassian.net/wiki/spaces/EEREF/pages/2380278/Open+Boundary+Condition

3

Thanks for your answer. I already did what you recommended, but unfortunately the problem continues. See the attached images. Any other suggestions? I appreciate your help in advance. Attached files

4

There are a number of possible issues:
1. at the open boundary you have one cell deactivated in one direction, and two in the other. It is better to make it two cell deactivated in both directions in the corners.
2. Inappropriate assignments of gradients of vertical densities at the open boundaries can cause problems. For example, if the differences between salinity at the top and bottom are too great it will lead to instability.
3. It could be that the bathymetry is not smooth at the open boundaries - we recommend the cell with open boundary and adjacent cell inside the model have the same bathymetry. Any variation in bathymetry between the open boundary and adjacent cells can lead to instability. In EE8.3 there will be a feature to automatically provide this smoothing.