Setting the Stopping Criteria

The solid model is highly nonlinear because of the nonlinear geometry, the hyperelastic model, and the contact. To improve the stability and convergence rate of the two-way coupled fluid-structure model, you apply the Dynamic stabilization method.

Specify the fluid-structure coupling settings:
  1. Select the Solvers > Fluid Structure Coupling node and Stabilization Method to Dynamic.
  2. Select the Fluid Structure Coupling > Displacement Convergence Tolerance node and set the Multiplier to 1.0E-100.
    Using a high value for the Displacement Convergence Tolerance ensures that the Solid Stress Solver solves at each inner iteration without terminating prematurely within the time-step.
  3. Select the Solvers > Implicit Unsteady node and make sure that Temporal Discretization is set to 1st Order.
Specify the morpher settings:
  1. Select the Solvers > Mesh Morpher node and set the following properties:
    Property Setting
    Boundary Layer Morphing Activated
    Morph At Inner Iterations Activated
Specify the Stopping Criteria settings:
  1. Select the Stopping Criteria node and set the following properties:
    Node Property Setting
    Displacement Criterion Logical Rule And
    Force Criterion Enabled Deactivated
    Maximum Inner Iterations Enabled Deactivated
    Maximum Physical Time Maximum Physical Time 4.0 s
  2. Right-click the Stopping Criteria node and select New Criterion > Minimum Inner Iterations.
  3. Select the Minimum Inner Iterations and set the following properties:
    Property Setting
    Minumum Inner Iterations 5
    Logical Rule And (Default)
The combination of stopping criteria guarantees that at the end of the time step, at least 5 or more iterations are executed and the displacement residual is below the default Minimum Limit of 1E-6.
  1. Select the Monitors > Displacement node and set Normalization Option to Off.
  2. Select the Force monitor and set Normalization Option to Off.
  3. Save the simulation.