Numerical modelling of interactions of waves and sheared currents with a surface piercing vertical cylinder

Abstract

Highlights • Two different approaches, 2-D OpenFOAM and Lagrangian wave-current simulations, are used to model focussed wave groups and sheared currents simultaneously in a controlled manner, and produce input conditions for 3-D OpenFOAM models to investigate wavecurrent-structure interactions. • Good agreement between numerical results and experimental data is obtained, indicating that both approaches are capable of replicating experimental wave-current flows, and accurately modelling interactions between surface piercing cylinders and focussing waves on sheared currents. • The performance of both approaches is evaluated in terms of accuracy and computational effort required. • It is found that the method of coupling 3-D CFD and Lagrangian models is computational slightly cheaper and slightly more accurate because of the use of a smaller computationally domain and the iterative wave-current generation in the faster Lagrangian model.

Numerical models for evolution of extreme wave groups

“…More specifically, the VoF model to be used to model the small region around the breaking crest, which allows to obtain a high mesh resolution with a relatively small number of mesh points and therefore with a low computational cost. As a first step, the Lagrangian and VoF coupled models were recently applied to fluid-structure interaction problems, which requires simpler coupling techniques, compared to a hybrid breaking model [44,23].…”

Extreme runup events around a ship-shaped floating production, storage and offloading vessel in transient wave groups

“…The experimental incident wave group is re-created with reasonable accuracy in the numerical wave tank (NWT) using an iterative method (see figure 2 and Chen et al. (2019 a ) for details). We note here that the total length of the NWT is minimized to save computational cost, while the width and the depth are kept the same as in the experiments.…”

“…The total length is set as with the model being placed away from the input boundary to allow wave propagation (Chen et al. 2019 a ). Here, is the peak wavelength (1.72 m in this work).…”

“…In this work, the maximum linear relative vertical wave runup at the bow is desired (Chen et al 2019c). The calibration is achieved in the experiments by applying the phase separation method in tandem with the iterative technique used in Chen et al (2019a). Utilizing the four-phase realizations (figure 2a), the linear free surface elevation (without the model in place) can be separated via addition and subtraction of the four signals and their Hilbert transform (Fitzgerald et al 2014).…”

“…We note here that the total length of the NWT is minimized to save computational cost, while the width and the depth are kept the same as in the experiments. The total length is set as ∼10λ p with the model being placed ∼3.5λ p away from the input boundary to allow wave propagation (Chen et al 2019a). Here, λ p is the peak wavelength (1.72 m in this work).…”