Application of a vortex tracking method to separated flow around marine structures

A vortex tracking method is presented. It is based on distributing sources and dipoles over boundaries and free shear layers. A boundary layer calculation is needed every time-instant to predict the separation points. The prime application in mind has been marine structures, but the method can also be applied to incompressible, high Reynolds-number flow around other types of structures. Advantages, disadvantages and difficulties with the method are discussed. In principle the method can handle any body configurations, including three-dimensional effects and free-surface effects. Difficulties are encountered with secondary separation, prediction of separation points and returning vorticity in ambient oscillatory flow. One important advantage with the continuous representation of the free shear layer is that it enables one to handle the shear layer in detail in the vicinity of separation points on continuously curved body surfaces. Examples of satisfactory prediction of forces on marine structures are given, but there exists a problem in very long time simulations. This is partly due to the detailed numerical description of the free shear layers.