Parametrisation for Unsaturated flow problem

[AKI]

I have a problem with my model parametrisation. I have 1D TOUGH EOS 3 model, where there is coppercanister as a heatsource in the left side, partlysaturated bentonite as a partlysaturated zone with normal pressure in the middle and a fully saturated rock zone with 1,2MPa pressure in the right side. There is two phases at the beginning in the bentonite and only waterphase in the rockzone. How I should made the parametrisation so that the model should run through the ten year period ?

My model crashes after 0.93 years when there happens gasphase forming in bentonite-rock interface in the side of rock matrix even if the rock matrix is parametrisized so that there is only one phase. The pressure is so high that there shouldn't be gasphase.

My model is attached here.

If you have any further questions, I would be willing to answer

Thanks for the help

Aku

saturation.zip

[swenson]

I have a problem with my model parametrisation. I have 1D TOUGH EOS 3 model, where there is coppercanister as a heatsource in the left side, partlysaturated bentonite as a partlysaturated zone with normal pressure in the middle and a fully saturated rock zone with 1,2MPa pressure in the right side. There is two phases at the beginning in the bentonite and only waterphase in the rockzone. How I should made the parametrisation so that the model should run through the ten year period ?

My model crashes after 0.93 years when there happens gasphase forming in bentonite-rock interface in the side of rock matrix even if the rock matrix is parametrisized so that there is only one phase. The pressure is so high that there shouldn't be gasphase.

My model is attached here.

If you have any further questions, I would be willing to answer

Thanks for the help

Aku

Aku,

The problem is related to the weighting options used at the grid block interfaces. See pages 135-136 of the TOUGH2 user manual for a discussion. In the Solution Controls dialog, select the Weighting tab. Change the Mobility at Interface to "Harmonic Weighted", The Permeability at Interface to "Harmonic Weighted", the Density at Interface to "Average of Adjacent Elements", and the Diffusive Flux at Interface to "Coupled Harmonic Weighting". Your problem will then run quickly and the solution appears reasonable.

However, it would be helpful to have a deeper discussion on the numerical solution that makes these changes in weighting necessary. Perhaps inviting Karsten Pruess to discuss this would be useful. You could send your model (the saturation.dat file) to him and ask.

Daniel Swenson, Thunderhead Engineering

[AKI]

Aku,

The problem is related to the weighting options used at the grid block interfaces. See pages 135-136 of the TOUGH2 user manual for a discussion. In the Solution Controls dialog, select the Weighting tab. Change the Mobility at Interface to "Harmonic Weighted", The Permeability at Interface to "Harmonic Weighted", the Density at Interface to "Average of Adjacent Elements", and the Diffusive Flux at Interface to "Coupled Harmonic Weighting". Your problem will then run quickly and the solution appears reasonable.

However, it would be helpful to have a deeper discussion on the numerical solution that makes these changes in weighting necessary. Perhaps inviting Karsten Pruess to discuss this would be useful. You could send your model (the saturation.dat file) to him and ask.

Daniel Swenson, Thunderhead Engineering

Hi Dan

Long time no see and thanks for the Help

I had already tried that, but when I do change the mobility at Interface to "Harmonic Weighted", the bentonite doesn't get saturated from water, which is what I would like to happen So I should have some other solution. I will try to ask Karsten what he thinks about the flow problem.

Thanks

Aku