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Conflict of initial values
Posted 5 juin 2014, 21:40 UTC−4 Porous Media Flow Version 4.4 3 Replies
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I've been trying to model flow in a cylindrical coal sample but my efforts have been in vain due to a conflict resulting from having two initial values in two separate physics. The physics consist of solid mechanics and poroelasticity. Poroelasticity is used to model poroelastic deformation and solid mechanics is used to model stresses and strains applied to the coal sample.
The problem is each physic contains initial values by default (not able to delete or inactive) that overlap each other which results a message error saying "Failed to find consistent initial values". I would appreciate it if someone can help me to fix this problem.
Cheers,
Nima
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I do not understand the set up of your problem...so my response has to be vague.
The poroelastic module should give you stress-strain behaviour because it is essentially a (linear elastic) solid mechanics module, but additionally coupled to pore pressure response. So why would you need an additional solid mechanics node?
In any case, if you have additional solid mechanics node, then do you have some sort of coupling between the poroelastic model with the new solid mechanics node? If yes, then I believe that you will have defined different names to the dependent variables so that COMSOL is not confused. Moreover, COMSOL will not let you have the same dependent variable name with different physics.
Failed to find consistent initial values is more to do with the ill posed initial or boundary condition. There are already some threads concerning this error type. Note that every pde physics node must have initial and boundary conditions or else how would you solve initial-boundary value problems.
Suresh
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Thanks very much for your time and helping me fix the problem. Now I know where the problem lies so I will remove discrete solid mechanics physic and I will incorporate all the stresses and boundary loads in poroelasticity physic through the solid mechanics defined in it. But the problem I'm having now is Storage Model is overridden by Poroelastic Material. To let you know further about the problem, I'm modelling permeability change and creep in a cylindrical coal sample saturated with methane and accommodated in the cell of a tri-axial apparatus that applies axial and confining pressures to the sample. Please find the attached file showing the geometry and boundary conditions of the problem. Thanks again for your help.
Cheers,
Nima
Attachments:
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I do not know what you mean, may be a screenshot of your problem will help.
Anyway the storage model should be within the Poroelasticity interface, is it not? So is there a need to define a separate storage model interface?
For example, in a storage model, you will need density, viscosity, porosity, permeability and compressibility. I thought that these should already be defined within the Poroelastic interface.
Suresh