Research On Hydrodynamic Performance Of Piples Under Oblique And Multi-directional Wave Action

With the exploitation of land resources getting saturated,more and more attention were paid to the exploitation and utilization of ocean.In order to make more efficient use of Marine resources,a large number of Marine structures have been built.Meanwhile,most of these Marine structures take pile as their foundation structure,and how to ensure the safety and stability of the pile structure has been widely concerned.In this study,the coupling model of OceanWave3D and OpenFOAM is used to simulate the hydrodynamic characteristics of piles under the action of oblique waves and multi-directional waves.Firstly,the difference of surface elevation,wave run-up around the piles and the wave load,which were under the action of regular wave with different angles,are compared.And then,the variation of the wave load and pile group coefficient on the piles with KC number and relative pile distance when the regular waves with different angles is systematically analyzed.Secondly,the influence of the main direction of multi-directional irregular wave on wave run-up around the piles is studied,and the influence of the wave directionality on wave run-up around the piles,wave load and pile group coefficient on piles is systematically analyzed.The results of the study indicate that for regular waves,when the wave is incident in the forward direction,the peaks or troughs act on all piles simultaneously.However,when the wave incidence is oblique,the peaks or troughs of the wave act on each pile asynchronously,which also leads to the fact that under the same situation,when the regular wave in the forward direction,the total force and pile group coefficient of total force on piles are greater than the obliquely incident wave.At the same time,when the wave incidence is oblique,the transverse force acting on the piles is greater than the forward incidence.In addition,the load and pile group coefficient of waves incident at different wave angles on piles vary with KC number and relative pile distance.For multi-directional irregular waves,the inline force acting on the piles varies less with the wave directionality,which is less than 10%.The transverse force increases with the decrease of the directional spreading parameter,and the maximum value of the transverse force is more than 2 times of the minimum value.At the same time,the inline force of the irregular wave on the piles decreases with the increase of the main direction of the wave,while the transverse force increases with the increase of the main direction of the wave.Finally,based on the two-phase dynamic mesh solver interDyMFoam in OpenFOAM,the sediment transport module was developed and coupled with OceanWave3D by considering both the suspended and bedload transport.By comparing with the data in the literature,it is verified that the developed sediment transport module can accurately simulate suspended mass transport and sediment erosion around the pile.The developed sediment transport module was used to simulate the erosion around piles when the wave direction angles were 0 ° and 30 ° respectively.It is found that the range and depth of the scour pit around the piles when the waves are incident normally are greater than when the waves are incident obliquely.