The present paper deals with the numerical simulation of a non-linear coupled fluid-structure problem with finite element/finite volume coupled technique and mainly focus on the time coupling algorithm: the coupling procedure lies on a staggered explicit or implicit strategy. A simple coupled case is studied; namely a non-linear elastic beam coupled with an incompressible fluid with free surface effects. The structure problem is solved with a finite element approach. The nonlinear discrete structure problem is integrated in time with the nonlinear Newmark scheme with a fixed-point procedure. The fluid problem is solved with a finite volume approach. The non-linear discrete fluid problem is solved with the PISO (Pressure Implicit by Splitting Operator) algorithm. The coupled problem is solved with two different approaches. At first, an explicit approach is proposed, based on a step by step alternate integration of the structure and fluid non-linear problems. As expected the method is found to be numerically dissipative and potentially unstable. An implicit approach is then proposed, using inner coupling iterations. The proposed algorithm is proved to be stable and less dissipative. Implicit and explicit approaches are presented. Numerical calculations are performed on the elementary studied case. Results are presented and compared for the two time-integration procedures, highlighting the numerical qualities of each procedure in terms of numerical damping, stability and precision.
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