Hi Martina,

Curiously my problems are more when I try steady state simulations than when I do transients. Transients have (almost) always converged.

In my problem I start with a given glacier geometry and temperature and I first relax the free surface (not solving for Temp) for 50-100 years (or more sometimes). Then I try to do a steaty state calculation for temperature (using TemperateIceSolver) using the velocity computed from the previous solution (so I only solve for Temp). Trying this in steady state does not work if I imposed sliding (constant Slip Coefficient) in my first run. If I had no sliding then no problem to get a steady state.

Funny thing about sliding is that I get sliding velocity higher than surface velocity at several nodes where bed elevation gradient is high. Don't know if anyone has observed that.

I tried two different initial conditions for temperature (one with a linear steady state) and one that takes into account advection. Neither helped to converge when trying the steady state.

I've turned off heat sources (friction, strain heating) but that does not help.

I have Loop While Unconstrained Nodes = False because, like you, having it True makes things worse.

The problem appears to come from advection. When that's off then I can get a steady state solution. When on the temperatures go crazy and the TemperateIceSolver does not converge.

Again this only happens when I have sliding with a constant Slip Coefficient.

I have tried turning off the heat flux at the base. First I tried with a fixed temperature and that converged in steady state (with sliding and advection on). Trying to put heat flux back on appears to work for fine meshes (I am still exploring here). So may be that's the way to go, too early to tell yet.

I've tried the temperature-dependent sliding law of Hakime et al. Greenland paper but that did not work for me so far. I tried it from the start (in my first run trying to relax the free surface) and may be that's not a good strategy.

I don't seem to have the problem of the free surface going below the bedrock. That's working well.

And yes possibly using Mesh Extrusion might help but I have not been able to make it work yet.

Thanks

Denis