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Nonconvergence of time dependent solver using dynamic compression equation
Posted Jan 28, 2014, 2:12 p.m. EST Mesh, Studies & Solvers Version 4.3b 1 Reply
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I am trying to implement dynamic compression to a 2D model using triphasic theory of cartilage, but I always get a singularity problem. The nonlinear solver is nonconvergent in the first time step of the time dependent solver. For the steady state case, static compression, I apply a strain_initial = -0.1, and the static case works. The initial value of the time dependent case is the solution of the steady state case. Then I add a strain = -0.025 * sin(2*pi*t*t_const*frequency).
I have tried refining the mesh (quadrilateral and triangular), lower the relative tolerance to 1e-6, and verified steps for the time dependent solver. The frequency is not too high, which is only 2.5%. Boundary conditions may not be complete, or the time-dependent dweak is wrong. Could you please help?
I have tried refining the mesh (quadrilateral and triangular), lower the relative tolerance to 1e-6, and verified steps for the time dependent solver. The frequency is not too high, which is only 2.5%. Boundary conditions may not be complete, or the time-dependent dweak is wrong. Could you please help?
1 Reply Last Post Feb 5, 2014, 2:53 p.m. EST
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Posted:
1 decade ago
I fixed the math equation for the dweak term, and it converges. Now I don't see any change in concentration profile after dynamic compression, as I used the solution of the stationary case as the initial condition of the dynamic case? Why?