Free surface flow simulation: correcting and benchmarking the ALE method in Code_Saturne

Abstract

The present thesis was written by Olivier Cozzi at the University of Manchester in pursuance of the degree of Master of Philosophy in 2010. It presents "Free surface flow simulation: correcting and benchmarking the ALE method in Code_Saturne", that is to say the implementation of free surface flows within Code_Saturne, an in-house code developed by EDF (Électricité de France) to solve CFD problems, using the Arbitrary Lagrangian Eulerian (ALE) method already embedded in this code. For a code like Code_Saturne, which aims at being easily implemented in a wide range of applications, the handling of free surface flows is critical because it extends the range of possible applications (tank filling, marine turbine interactions with waves and currents, water supply and reject points ...). Up to now, the ALE module within Code_Saturne was only used for fluid coupling with a solid structure; thus we had to adapt it to free-surface flows by adding a convergence loop to perform the free surface movement incrementally within each time step. Afterwards, the geometry was updated at the outer iterations level by imposing the displacement of each cell-vertex within the global domain: the cell-vertex motion is then computed for the free-surface cell-vertices in the first place and for the internal cell-vertices secondly. The new free-surface module was then implemented to three different test cases: a standing wave in a tank (unsteady test case with a periodic analytic solution), a solitary wave in a tank (unsteady test case with an analytic solution), a submerged hydrofoil (steady test case with experimental measurements). The results are encouraging and the feasibility is clearly demonstrated. Some limitations still exist - mainly caused by the inaccurate interpolation performed by Code_Saturne between the free-surface cell-vertex displacement and the free-surface cell-face centre velocities - but these could be eliminated during the next stages of the project.

Date of Award	1 Aug 2011
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Peter Stansby (Supervisor)