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1D PDE coupled to 2D edge load of solid mechanics
Posted Jun 21, 2010, 12:49 p.m. EDT 1 Reply
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I have been using the general form PDE and the 1D PDE model alone seems to work fine by itself. As does the 2D solid mechanics model with any sort of independent edge loading applied.
This is a fluid-structure interaction problem. The 1D momentum equation should be dependent on the deformation of the 2D solid and the 2D solid edge load should be the resulting pressure calculated from the 1D momentum equation.
When I solve the problems individually, I can plot fluid velocity and pressure versus the x-coordinate fine and the results seem reasonable, as does the 2D solid mechanics model.
I have two solver sequences that are time-dependent, but that only calculate the initialization. One for the 1D PDE model and another for the 2D solid mechanics model. So I calculate the solid domain with 0 Pa edge load first, then calculate the 1D PDE solution with an assumed (e.g. constant) initial shape of the solid (assumed, because attempts to couple the actual displacement of the edge such as y+v or genext1(y+v) or y+genext1(v) have all failed with errors).
The difficulty arises when I attempt to couple the resulting pressure to a follower pressure edge load boundary condition on a 2D solid mechanics model.
I receive the following error:
Failed to evaluate variable Jacobian.
- Variable: mod1.prs
- Geometry: 2
- Boundary: 3
Model 1 or mod1 is the 1D PDE and model 2 is the solid mechanics model. Boundary 3 of geometry 2 is the edge I want to apply the pressure loading to on the solid mechanics model.
mod1.prs is simply the general extrusion of the pressure term from the 1D PDE entered as: genext2(p) where the source of genext2 is defined over the entire domain of the 1D geometry.
I understand that failing to evaluate the Jacobian generally indicates that COMSOL cannot find the variable, in this case, mod1.prs. However, I am able to plot mod1.prs
Any ideas?
Hello Dan Lo Forte
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I had the same error when I tried to use an interpolation function as follower pressure in a boundary load condition. The mistake was simply that I forgot to specify the arguments, i.e. I wrote "int1" instead of "int1(x,y)", where int1 was the name of the function (not of the branch in the tree).
Could something like this be the case in your model?
Best regards,
Oliver Nemitz