[kkpal]

Dear all, currently I'm modifying the wingMotion case in the tutorial to a 2D circular cylinder. The main work in the modification lies in the pointDisplacement file. The cylinder is supposed to vibrate only in the y-axis(due to lift force). So I used the following lines:

constraints
        {
            maxIterations   500;

            fixedLine1
            {
                sixDoFRigidBodyMotionConstraint fixedLine;
                tolerance        1e-9;
                relaxationFactor 0.7;
                fixedLineCoeffs
                {
                    refPoint      (0 0 0.025);
                    direction     (0 1 0);
                }
            }



            
        }
        restraints
        {
            verticalSpring
            {
                sixDoFRigidBodyMotionRestraint linearSpring;

                linearSpringCoeffs
                {
                    anchor          (0 0 0.025);
                    refAttachmentPt (0 0 0.025);
                    stiffness       6;
                    damping         0.1;
                    restLength      0;
                }
            }

        }

The simulation could proceed however I kept getting error message in each timestep saying things like this: "Constraint fixedLine1 error (0.000620122258 0 0) force (-0.0489759093 -0 -0) moment (0 0 0) not converged".
What does this message mean??