Hi Elmers,
I have troubles with an iceshelf model (prognostic, 2D, flowline, no grounding line). I start from a block, prescribe the flux at the back and the pressure at the bottom & front. I do get nice steady state profiles, however, the final shape unfortunately depends strongly on the timestepping size and the spatial gridding (I attached a snapshot for dt=0.03,0.1,0.3 years). The system becomes more instable when increasing the horizontal resolution; using the NormalTangential Velocity at the bottom does not work.
Does anybody have experience with simple iceshelf models that do not include a grounding line? I would be grateful if somebody could have a look at the attached zip file ("make compile all2d" should make it run).
Greetings, Reinhard
2d Ice Shelf without Grounding Line
2d Ice Shelf without Grounding Line
 Attachments

 IS2D_example.zip
 (25.29 KiB) Downloaded 1275 times

 Is2d_screenshot.png
 (52.86 KiB) Not downloaded yet
Re: 2d Ice Shelf without Grounding Line
Hi Reinhard,
I had a look in your sif file. Did you check that you really have a constant flux in your inflow boundary?
If you really have constant BC then i would expect that the steady solution is not a function of the time step...
Regards
Olivier
I had a look in your sif file. Did you check that you really have a constant flux in your inflow boundary?
If you really have constant BC then i would expect that the steady solution is not a function of the time step...
Regards
Olivier
Re: 2d Ice Shelf without Grounding Line
Hi Olivier,
thanks for the quick reply. To prescribe the flux, I scale the xvelocity in the incoming BC with the ice thickness of the current time step. I double checked (depth+height)*velocity_X in Paraview and it stays constant at the inflow boundary (x=0). However, for the case of zero accumulation the flux varies by about 3 % for x>0. Something is still wrong here.
thanks for the quick reply. To prescribe the flux, I scale the xvelocity in the incoming BC with the ice thickness of the current time step. I double checked (depth+height)*velocity_X in Paraview and it stays constant at the inflow boundary (x=0). However, for the case of zero accumulation the flux varies by about 3 % for x>0. Something is still wrong here.
Re: 2d Ice Shelf without Grounding Line
To finish this thread: As suspected by Olivier the Case more or less works. I did some more testing with with the time stepping and the horizontal resolution and it turns out that for a given grid the solution is consistent if the time steps are small enough (e.g. 0.05 and below). I still have problems when using the NormalTangential Velocity coordinate system at the iceshelf bottom as indicated in the "buoyancy" documentation.