Spiky Ice Sheet Surface in transient flow line model
Posted: 02 Jun 2020, 21:27
Hi all,
I have been trying to run a thermo-mechanically coupled transient land-terminating flowline model based on an EISMINT test (i.e. no flow bottom, SMB(x), Surface Temp(y), no ice at the start). The setup is fairly basic, it is really just a modified version of the transient toy flowline example model on a larger flat bed. My issue is that as the simulation progresses, the surface of the ice sheet oscillates, and when the ice sheet approaches a steady-state profile it settles into a fixed spiky pattern. The spikiness causes errors in the velocity solution which in turn causes errors in the temperature solution. I know that increasing the mesh resolution near the terminus localizes the effects of the problem to near the terminus. This indicates that the instability stems from the terminus. The reason for not wanting to increase the mesh resolution is that because the terminus if free to move, a large portion of the domain must be run at a finer mesh resolution resulting in simulations that are prohibitively slow with my current computer setup.
My question is, is there a way to alleviate this problem so as to get more reasonable solutions while still using a relatively course mesh resolution?
Thanks,
I have attached an image from 40 thousand years into a 10km horizontal resolution simulation, as well as the sif, and the geo file to generate the mesh used in this simulation.
In the figure, the ice sheet is approximately 3km tall at the divide and 500 km long.
I have been trying to run a thermo-mechanically coupled transient land-terminating flowline model based on an EISMINT test (i.e. no flow bottom, SMB(x), Surface Temp(y), no ice at the start). The setup is fairly basic, it is really just a modified version of the transient toy flowline example model on a larger flat bed. My issue is that as the simulation progresses, the surface of the ice sheet oscillates, and when the ice sheet approaches a steady-state profile it settles into a fixed spiky pattern. The spikiness causes errors in the velocity solution which in turn causes errors in the temperature solution. I know that increasing the mesh resolution near the terminus localizes the effects of the problem to near the terminus. This indicates that the instability stems from the terminus. The reason for not wanting to increase the mesh resolution is that because the terminus if free to move, a large portion of the domain must be run at a finer mesh resolution resulting in simulations that are prohibitively slow with my current computer setup.
My question is, is there a way to alleviate this problem so as to get more reasonable solutions while still using a relatively course mesh resolution?
Thanks,
I have attached an image from 40 thousand years into a 10km horizontal resolution simulation, as well as the sif, and the geo file to generate the mesh used in this simulation.
In the figure, the ice sheet is approximately 3km tall at the divide and 500 km long.