Experimental and numerical investigations of the flow around an oar blade

This article aims at verifying the capabilities of a Reynolds-Averaged Navier-Stokes Equations (RANSE) solver (ISIS-CFD, developed at the Fluid Mechanics Laboratory of Ecole Centrale de Nantes [LMF]) to accurately compute the flow around an oar blade and to deduce the forces on it and other quantities such as efficiency. This solver is structurally capable of computing the flow around any blade shape for any movement in six degrees of freedom, both when the blade pierces the free surface of the water and when it does not. To attempt a first validation, a computation was performed for a simplified case chosen among those for which experimental results are available at LMF. If results prove satisfactory for a simplified blade shape and for a movement that respects the main characteristics of blade kinematics, then the solver could be used for real oars and more realistic kinematics. First, the experimental setup is considered, and the objectives, methodologies, and procedures are elucidated. The choice of the test case for numerical validation is explained, i.e., a plane rectangular blade with a constant immersion and a specified movement deduced from analogy with tests on propellers. Next, the numerical framework is presented and the Navier-Stokes solver and methods for handling multifluid flows and moving bodies are described. Lastly, numerical results are compared with experimental data, highlighting an encouraging agreement and proving the relevance and the complementarity of both approaches.