Search found 10 matches

by ChristianB
23 Jan 2015, 11:02
Forum: Elmer/Ice
Topic: Non-smooth weertman basal velocity
Replies: 2
Views: 6139

Re: Non-smooth weertman basal velocity

Hi Rupert, Thanks for the reply. I am using a constant basal drag coefficient. You are right that on a small scale the bedrock is not smooth, however, I use 200 meter spacing between nodes (square grids for the moment) so on that scale it should be "smooth". I think I will try your suggest...
by ChristianB
22 Jan 2015, 17:51
Forum: Elmer/Ice
Topic: Non-smooth weertman basal velocity
Replies: 2
Views: 6139

Non-smooth weertman basal velocity

Hi all, I have been getting some sliding velocities that look a bit strange to me using the Weertman relation. They are however not completly unrealistic and wanted to hear if other users are seeing similar sliding patterns. It looks similar to the post: Small basal velocity value patch from Adjoin ...
by ChristianB
26 Sep 2014, 10:47
Forum: Elmer/Ice
Topic: Setting basal pressure til fraction of overburden
Replies: 5
Views: 9208

Re: Setting basal pressure til fraction of overburden

Hi Gag, Thanks for the reply. I have been playing with both weertman and coulomb friction which is the reason for why I would like to add a simple basal pressure. Although weertman does not depend on basal pressure it is quite simple compared to coulomb friction. I therefore started with setting pre...
by ChristianB
23 Sep 2014, 15:01
Forum: Elmer/Ice
Topic: Setting basal pressure til fraction of overburden
Replies: 5
Views: 9208

Re: Setting basal pressure til fraction of overburden

Yes, I am trying the weertman sliding law. I had the same though with units because my output is in MPa. But when I apply the External Pressure in MPa my basal pressures are on the order of ice overburden and not 0.6*overburden. So it seems that the pressure BC is not enforced in that case. I am usi...
by ChristianB
23 Sep 2014, 11:39
Forum: Elmer/Ice
Topic: Setting basal pressure til fraction of overburden
Replies: 5
Views: 9208

Setting basal pressure til fraction of overburden

Hi, I am trying to set the basal pressure equal to 60% of my ice overburden pressure. My domain contains both ice-covered and ice-free areas. So far I have tried setting external pressure on the basal boundary everywhere like this, External Pressure = Variable ZsDEM, bedrockDEM Real MATC "(tx(0...
by ChristianB
10 Jun 2014, 14:17
Forum: Elmer/Ice
Topic: Mask to restrict sliding in ice free areas
Replies: 10
Views: 17733

Re: Mask to restrict sliding in ice free areas

Thanks for the suggestion Martina. I have tried playing around with the mesh but it is quite difficult debugging mesh problems. The flowdepth solver does not work at the moment (had it working previously) so there must be something with the mesh. I have tried using ElmerPOST but the mesh is quite bi...
by ChristianB
23 May 2014, 15:10
Forum: Elmer/Ice
Topic: Mask to restrict sliding in ice free areas
Replies: 10
Views: 17733

Re: Mask to restrict sliding in ice free areas

So I tried the different suggestions and that did help a bit. I am now able to converge but the result is clearly wrong. The computational time also increased quite a lot (which I was also expecting with the boundary condition). So I am now running Elmer in parallel with Hypre, but that should hopef...
by ChristianB
20 May 2014, 10:32
Forum: Elmer/Ice
Topic: Mask to restrict sliding in ice free areas
Replies: 10
Views: 17733

Re: Mask to restrict sliding in ice free areas

Sorry for the late reply. Have been without internet for a couple of weeks.

Thanks for all the suggestions. I have all week to play with Elmer so I will try the suggestions and write back about the outcome.

Martina: I will try the normal Navier-Stokes solver at some point and see what happens.
by ChristianB
01 May 2014, 05:05
Forum: Elmer/Ice
Topic: Mask to restrict sliding in ice free areas
Replies: 10
Views: 17733

Re: Mask to restrict sliding in ice free areas

Thanks for the suggestion thomas. Unfortunately it did not help. To reduce the complexity of my model I changed to a Weertman sliding law and forced a constant sliding coefficient of 10.0E00. That should in practis result in a no-sliding condition everywhere. But also in this "simplere" ca...
by ChristianB
29 Apr 2014, 02:01
Forum: Elmer/Ice
Topic: Mask to restrict sliding in ice free areas
Replies: 10
Views: 17733

Mask to restrict sliding in ice free areas

Hi Everyone, I am trying to get columb-friction sliding running on a model of a small'ish glacier I am currently working on. I am using the ParStokes solver but it keeps diverging when I activate the CF law. From reading on the forum I have been trying to write a mask to restrict sliding in areas wi...