Author(s): Santiago Martelo

Linked Author(s):

Keywords: Interfacial Flows; Fluid-Structure Interaction

Abstract: This work presents a numerical investigation of the vortex induced vibrations caused by currents and waves on cylinders of various shapes piercing the sea surface. Through three-dimensional Large-Eddy Simulations (LES) coherent turbulent structures were identified that may lead to Vortex Induced Vibrations. VIV can be found in many engineering applications like risers, support pylons in bridges and piers, mooring lines of floating structures and spar-type floating wind turbines. It is important to assess the total forces and range of motion caused by vortex shedding to avoid fatigue and extend the operational life of the underwater structure. The shape of the structures considered in this paper are namely circular and square cylinders. Thus simulations are run to assess the combined effect of current and waves on the structure. The finite differences code Hydro3D was employed to carry out these simulations using the Smagorinsky LES model. In the past, this code has been validated for free surface flows and fluid-structure interaction using the Level-Set and Immersed Boundary methods, respectively. Such models have been applied to study a number of hydraulic engineering and marine energy applications. This computational code solves the Navier Stokes Equations using a staggered grid for the pressure field and the Cartesian components of velocity. The fractional step method is used in this code to advance in time the fluid properties combined with Runge-Kutta like and Crank-Nicolson schemes to evaluate the convective and diffusive terms. The Poisson pressure-correction equation is solved using a multi-grid technique based on the TDMA method in the final step as a corrector of the predicted velocities and pressure fields. This article depicts a new fluid-structure interaction model inspired in the ghost cell approach.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221726

Year: 2022