Viscoelastic flow simulations are intrinsically nonlinear, and the non-linearity originates at first from the constitutive equations. Defining the appropriate evolution scheme for these non-linearities is usually helpful for obtaining solutions, however, it is sometimes convenient to enable an automatic convergence strategy for viscoelasticity. You can do this using the Enable convergence strategy for viscoelasticity option. The solver adjusts the appropriate settings in order to reach the solution. When selecting this strategy, the robustness of the calculation scheme is favored over the efficiency.

The convergence strategy for viscoelasticity can be combined with other convergence strategies for thermal flows or evolution on moving boundaries, when necessary. However, there are simulation cases which would require applying the convergence strategies along a specific sequence. When this is the case, reasonable practice would suggest starting with the evolution on moving boundaries; and to terminate the calculation with the convergence strategy for thermal flows.