COMPUTATIONAL FLUID DYNAMICS FOR THE SIMULATION OF OIL RECOVERY SYSTEMS AT HIGH SEAS

摘要

The paper presents multi-phase CFD-Calculations for simulating oil skimming processes in heavy seas.rnDuring the last years tanker catastrophes showed the shortcomings of existing oil recovery systems, especially while operating in heavy seas. For developing new and more efficient devices complex and expensive model tests must be conducted under special conditions to prevent environmental pollution. To minimize these costs CFD-tools for multi-phase flow simulations have been developed, and are applied to analyse and optimize oil recovery devices.rnThe analysis of local flow phenomena dependent on the motion of an oil recovery system in a given sea state are the basis for the development of an optimized oil recovery device. For this purpose, existing nonlinear numerical methods used for stationary and unsteady viscous computation (based on Volume of Fluid (VOF) methods and Reynolds Averaged Navier Stokes Equations (RANSE)) are enhanced and combined to simulate two-phase (air, water) and three-phase-flow (air, water, oil).rnNew methods for simulating motions in three (2D) and six degrees (3D) of freedom as well as for the generation of waves - regular and irregular sea states - are developed.rnTo increase the speed of calculation the RANSE/ VOF-method is coupled with a Potential theory method using Finite Element discretization (Pot/FE). Combining the advantage of the Pot/FE-solver, i.e. calculation speed, with the possibilities of the RANSE/ VOF-solver to simulate multi-phase flow and free body motion offers the opportunity to simulate a complete test in reasonable time.rnTo validate the procedure, the numerical simulations are compared to WAMIT-calculations and model tests carried out in a physical wave tank.