I'm trying to simulate a contracting left ventricle with a working aortic valve (implemented using 2-way FSI). To cut down on complexity, the simulation is 2D at the moment. I can achieve accurate wall motion, but upon implementing the valve my mesh fails due to negative cell volume. I've implemented the 2.5D remeshing strategy, and hoped that it would maintain mesh quality as the leaflets open up as well as help with issues involving negative cell volume. No such luck, as the mesh does not appear to be actively remeshing.
Here is a list of the parameters I've set/are working with:
- In the Dynamic Mesh options, Smoothing and Remeshing are enabled.
- Under Smoothing, I'm using the Spring/Laplace/Boundary Layer method, as this is what works with 2.5D remeshing (Note for other students: According to the manual, face region remeshing will only work with the Spring/Laplace/Boundary Layer method).
- The Spring Constant Factor is set to 0.1 (Although this apparently is negligible with iterations>100).
- The Convergence Tolerance is set to 0.001.
- The Number of Iterations is set to 100 (I've attempted changing this number, but have not noticed a significant change.
- The Laplace Node Relaxation is set to 0.5.
- Under Remeshing, the only method enabled is 2.5D. The Minimum Length Scale is set to 0.04 mm and the Maximum Length Scale is 0.71 mm (in the Mesh Scale Info, the min and max are 0.044 mm and 0.71 mm, respectively). I know ANSYS recommends setting the min and max scale at 0.4 and 1.4 of their Mesh Scale Info values, respectively, but even after I did that I was not getting good remeshing.
- The Maximum Skewness is 0.5 (0.53 in the Mesh Scale Info)
- As this is a 2D case, the "top" and "bottom" of the domain have been set to Symmetry in the Boundary Conditions
- In the Dynamic Mesh Zones, both leaflets are set to System Coupling, and have Solution Stabilization enabled.
- The symmetry regions are set to deforming
- Under Geometry Definition, the plane definition is used, with appropriate points on each plane set
- Under the Meshing Options, both have Smoothing enabled, but only one has remeshing enabled (as per instructed by the manual)
- The Min and Max length scale, and Maximum Skewness are the same as previously described
- The time step size is 0.0005 s.
The only thing that I can think of at this point is that the issues I'm having is a direct result of the meshing strategy I implemented (Adaptive Sizing used, element size of 0.5 mm, and a Linear Element Order). I can provide more info if need be.
If anyone has any suggestions, I'd love to hear it.