Transient large strain contact modelling: A comparison of contact techniques for simultaneous fluid–structure interaction

• A true-transient contact modelling method for FSI simulations is presented.
• Transient FSI contact modelling is necessary to predict fluid dynamics.
• Transient FSI modelling is necessary to predict structural deformation.

Contact between two deformable structures, driven by applied fluid-pressure, is compared for an existing pseudo-transient contact method (the default in the Comsol Multi-physics v3.3 software package) and a new transient method. Application of the new method enables time-dependent and simultaneous Fluid–Structure Interaction (FSI) simulations to be solved. The new method is based on Hertzian contact. It enables truly transient simulations, unlike the default contact method. Both the default and new methods were implemented using a moving Arbitrary-Lagrange–Euler mesh, along with velocity constraints and Lagrange Multipliers to enable simultaneous FSI simulations. The comparison was based on a simple two-dimensional model developed to help understand the opening of a heart valve. The results from the new method were consistent with the steady-state solutions achieved using the default contact method. However, some minor differences in fluid dynamics, structural deformation and contact pressure predicted were obtained. The new contact method developed for FSI simulations enables transient analysis, in contrast to the default contact method that enables steady state solutions only.