Problems with Constraint Correction

[Jana371]

Hi,
I am trying to build a simulation where two deformable objects collide (a catheter and a blood vessel). Mostly, I've been using one of the example files of the BeamAdapter Plugin as template and replacing the vessel mesh with my own flexible model. However, when I try to open the file, I get the following error message:

[ERROR] [LinearSolverConstraintCorrection(LinearSolverConstraintCorrection)] Can not use the solver linear_solver because it is templated on GraphScatteredType

When I try to run the simulation, it freezes pretty much instantly.

Here is some of my code for better understanding:

`rootNode.addObject('FreeMotionAnimationLoop')

rootNode.addObject('LCPConstraintSolver', mu='0.1', tolerance='1e-10', maxIt='1000', build_lcp='false')
rootNode.addObject('CollisionPipeline', draw='0', depth='6', verbose='1')
rootNode.addObject('BruteForceBroadPhase', name='N2')
rootNode.addObject('BVHNarrowPhase')
rootNode.addObject('LocalMinDistance', contactDistance='0.1', alarmDistance='0.5', name='localmindistance', angleCone='0.2')
rootNode.addObject('CollisionResponse', name='Response', response='FrictionContactConstraint')`

SimpleVessel.addObject('EulerImplicitSolver', name='cg_odesolver', rayleighStiffness=0.1, rayleighMass=0.1) SimpleVessel.addObject('CGLinearSolver', name='linear_solver', iterations=25, tolerance=1e-09, threshold=1e-09) SimpleVessel.addObject('LinearSolverConstraintCorrection', linearSolver="@linear_solver")

When looking for solutions, I came across similar discussion threads (#3046, #5187 and #3830), but after reading them I'm still not sure what exactly I need to change. Do I need a different ConstraintCorrection or have I forgotten to add something else?

Thanks!

[alxbilger]

Hi,

use a direct linear solver such as SparseLDLSolver or EigenSimplicialLDLT instead of CGLinearSolver. If you only simulate beams under the ODE solver, you can use the optimized BTDLinearSolver.

[Jana371]

Thank you! It's running now, albeit very slow but that's fine for now. As soon as the two objects collide I get the following warning over and over: [WARNING] [SparseLDLSolver(linear_solver)] partial_solve is not implemented yet. It's the same with the EigenSimplicialLDTL and the simulation keeps running in both cases. Do you know what I can do about that? I couldn't find much in the documentation, but maybe I just haven't looked in the right places.

[alxbilger]

I am not sure, but try to replace LinearSolverConstraintCorrection by GenericConstraintCorrection.

It's slow, what is the size of your problem? How many dofs?