ABSTRACT
A non-hydrostatic numerical model is employed to simulate focusing waves interaction with a fixed vertical cylinder. The model employs the finite volume method to discretize the Reynolds-Averaged Navier- Stokes Equations and the immersed boundary method is adopted to address cylinder surface. Consistent with the experimental set-up, the computation domain is 50.0m long, 2.2m wide with a water depth of 0.7m and a fixed cylinder is 0.22m diameter and 1m height. Focused waves are generated with the second order Schäffer correction method in this model. Then, the surface elevations at different locations and pressures on the cylinder are compared with the existing experimental results. The results show the non-hydrostatic numerical model can simulate the interaction process between focusing wave and fixed vertical cylinder accurately.
In recent years, many coastal and offshore structures have been constructed for energy demand. These structures usually face harsh environment. An example is the Draupner Jacket platform located in the North Sea on January 1st, 1995, with a maximum crest elevation of 18.5m and wave height near 26m (Haver and Anderson, 2000). Therefore, Understanding the hydrodynamic of wave structure interaction is very important for design and safety operation of coastal and offshore structures.
One of the common approaches to study this problem is analytical methods. Although many methods have been proposed (Morison et al., 1950; MacCamy and Fuchs, 1954; Faltinsen et al., 1995; Kriebel, 1998) to calculate wave force, it does not provide complete pressure distributions on these bodies. Furthermore, it remains questionable whether these available theories can be useful for predictions of wave forces under freak waves.
To overcome this, some researchers (Chaplin et al., 1997; Krokstad et al., 1998; Martin et al., 2001; Ma et al., 2009) carry out their work by physical tank testing. The advantage of this method is that the real hydrodynamics are modelled and can be measured. Also, it is quick to carry out a large number of tests with experimental method. However, to obtain representative data sets this might well be necessary, as only a certain number of wave gauges and pressure sensors can be placed in the flow without affecting it. More importantly, scaling effects from model to full scale might occur as well.
