Numerical simulation of wave interaction with a pair of fixed large tandem cylinders subjected to regular non-breaking waves

2021 ◽  
pp. 1-34
Author(s):  
Mohammad Mohseni ◽  
Carlos Guedes Soares
Keyword(s):  
Circular Cross Section ◽  
Wave Interaction ◽  
Breaking Waves ◽  
Navier Stokes ◽  
Two Phase ◽  
Wave Amplification ◽  
Vof Model ◽  
Stokes Waves ◽  
Truncated Cylinders ◽  
Fifth Order

Abstract This paper presents the application of a two-phase Computational Fluid Dynamics (CFD) model to carry out a detailed investigation of nonlinear wave field surrounding a pair of columns placed in the tandem arrangement in the direction of wave propagation and corresponding harmonics. The numerical analysis is conducted using the Unsteady Reynolds-Averaged Navier-Stokes/VOF model based on the OpenFOAM framework combined with the olaFlow toolbox for wave generation and absorption. For the simulations, the truncated cylinders are assumed vertical and surface piercing with a circular cross-section subjected to regular, non-breaking fifth-order Stokes waves propagating with moderate steepness in deep water. Primarily, the numerical model is validated with experimental data for a single cylinder. Future, the given simulations are conducted for different centre-to-centre distances between the tandem large cylinders. The results show the evolution of a strong wave diffraction pattern and consequently, high wave amplification harmonics around cylinders are apparent.

Numerical Simulation of Wave Interaction With a Pair of Fixed Large Tandem Cylinders Subjected to Regular, Non-Breaking Waves

2021 ◽  
Author(s):  
M. Mohseni ◽  
C. Guedes Soares
Keyword(s):  
Numerical Model ◽  
Wave Field ◽  
Circular Cross Section ◽  
Wave Interaction ◽  
Breaking Waves ◽  
Wave Loading ◽  
Two Phase ◽  
Wave Regime ◽  
Wave Amplification ◽  
Vof Model

Abstract The wave interaction with cylinders placed in proximity results in significant modification of the wave field, wave-induced processes, and wave loading. The evaluation of such a complex wave regime and accurate assessment of the wave loading requires an efficient and accurate numerical model. Concerning the wave scattering types identified by Swan et al. (2015) and lateral progressive edge waves, this paper presents the application of a two-phase Computational Fluid Dynamics (CFD) model to carry out a detailed investigation of nonlinear wave field surrounding a pair of columns placed in the tandem arrangement in the direction of wave propagation and corresponding harmonics. The numerical analysis is conducted using the Unsteady Reynolds-Averaged Navier-Stokes/VOF model based on the OpenFOAM framework combined with the olaFlow toolbox for wave generation/absorption. For the simulations, the truncated cylinders are assumed vertical and surface piercing with a circular cross-section subjected to regular, non-breaking fifth-order Stokes waves propagating with moderate steepness in deep water. Primarily, the numerical model is validated with experimental data provided by ITTC (OEC)[1] for a single cylinder. Future, the given simulations are conducted for different centre-to-centre distances between the tandem large cylinders. The results show the evolution of a strong wave diffraction pattern and consequently high wave amplification harmonics around cylinders are apparent.

scholarly journals Transport due to Transient Progressive Waves

2019 ◽  
Vol 49 (9) ◽  
pp. 2323-2336
Author(s):  
Juan M. Restrepo ◽  
Jorge M. Ramirez
Keyword(s):  
Breaking Waves ◽  
Stokes Drift ◽  
Lagrangian Model ◽  
Navier Stokes ◽  
Lagrangian Description ◽  
Transient Waves ◽  
Two Phase ◽  
Transient Transport ◽  
The Mean ◽  
Progressive Waves

AbstractMaking use of a Lagrangian description, we interpret the kinematics and analyze the mean transport due to numerically generated transient progressive waves, including breaking waves. The waves are packets and are generated with a boundary-forced, air–water, two-phase Navier–Stokes solver. These transient waves produce transient transport, which can sometimes be larger than what would be estimated using estimates developed for translationally invariant progressive waves. We identify the critical assumption that makes our standard notion of the steady Stokes drift inapplicable to the data and explain how and in what sense the transport due to transient waves can be larger than the steady counterpart. A comprehensive analysis of the data in the Lagrangian framework leads us to conclude that much of the transport can be understood using an irrotational approximation of the velocity, even though the simulations use Navier–Stokes fluid simulations with moderately high Reynolds numbers. Armed with this understanding, it is possible to formulate a simple Lagrangian model that captures the mean transport and variance of transport for a large range of wave amplitudes. For large-amplitude waves, the parcel paths in the neighborhood of the free surface exhibit increased dispersion and lingering transport due to the generation of vorticity. We examined the wave-breaking case. For this case, it is possible to characterize the transport very well, away from the wave boundary layer, and approximately using a simple model that captures the unresolved breaking dynamics via a stochastic parameterization.

scholarly journals VALIDATION OF A BUOYANCY-MODIFIED TURBULENCE MODEL BY NUMERICAL SIMULATIONS OF BREAKING WAVES OVER A FIXED BAR

2018 ◽  
pp. 71
Author(s):  
Brecht Devolder ◽  
Peter Troch ◽  
Pieter Rauwoens
Keyword(s):  
Numerical Simulations ◽  
Wave Breaking ◽  
Surf Zone ◽  
Breaking Waves ◽  
Navier Stokes ◽  
Two Phase ◽  
Numerical Wave Flume ◽  
Wave Flume ◽  
Nearshore Sediment Transport ◽  
Run Up

The surf zone dynamics are governed by important processes such as turbulence generation , nearshore sediment transport , wave run-up and wave overtopping at a coastal structure. During field observations , it is very challenging to measure and quantify wave breaking turbulence . Complementary to experimental laboratory studies in a more controlled environment , numerical simulations are highly suitable to understand and quantify surf zone processes more accurately. In this study, wave propagation and wave breaking over a fixed barred beach profile is investigated using a two­ phase Navier-Stokes flow solver. We show that accurate predictions of the turbulent two-phase flow field require special attention regarding turbulence modelling. The numerical wave flume is implemented in the open­ source OpenFOAM library. The computed results (surface elevations , velocity profiles and turbulence levels) are compared against experimental measurements in a wave flume (van der A et al., 2017) .

scholarly journals Numerical Simulations of Non-Breaking, Breaking and Broken Wave Interaction with Emerged Vegetation Using Navier-Stokes Equations

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2561 ◽  
Author(s):  
Xuefeng Zou ◽  
Liangsheng Zhu ◽  
Jun Zhao
Keyword(s):  
Wave Propagation ◽  
Wave Height ◽  
Wave Breaking ◽  
Surf Zone ◽  
Stokes Equations ◽  
Wave Interaction ◽  
Breaking Waves ◽  
Breaking Point ◽  
Navier Stokes ◽  
Inertia Force

Coastal plants can significantly dissipate water wave energy and services as a part of shoreline protection. Using plants as a natural buffer from wave impacts remains an attractive possibility. In this paper, we present a numerical investigation on the effects of the emerged vegetation on non-breaking, breaking and broken wave propagation through vegetation over flat and sloping beds using the Reynolds-average Navier-Stokes (RANS) equations coupled with a volume of fluid (VOF) surface capturing method. The multiphase two-equation k-ω SST turbulence model is adopted to simulate wave breaking and takes into account the effects enhanced by vegetation. The numerical model is validated with existing data from several laboratory experiments. The sensitivities of wave height evolution due to wave conditions and vegetation characteristics with variable bathymetry have been investigated. The results show good agreement with measured data. For non-breaking waves, the wave reflection due to the vegetation can increase wave height in front of the vegetation. For breaking waves, it is shown that the wave breaking behavior can be different when the vegetation is in the surf zone. The wave breaking point is slightly earlier and the wave height at the breaking point is smaller with the vegetation. For broken waves, the vegetation has little effect on the wave height before the breaking point. Meanwhile, the inertia force is important within denser vegetation and is intended to decrease the wave damping of the vegetation. Overall, the present model has good performance in simulating non-breaking, breaking and broken wave interaction with the emerged vegetation and can achieve a better understanding of wave propagation over the emerged vegetation.

Current generation by deep-water breaking waves

2016 ◽  
Vol 803 ◽  
pp. 275-291 ◽  
Author(s):  
N. E. Pizzo ◽  
Luc Deike ◽  
W. Kendall Melville
Keyword(s):  
Wave Field ◽  
Water Column ◽  
Deep Water ◽  
Stokes Equations ◽  
Laboratory Data ◽  
Breaking Waves ◽  
Navier Stokes ◽  
Mean Flow ◽  
Two Phase ◽  
Navier Stokes Equations

We examine the partitioning of the energy transferred to the water column by deep-water wave breaking; in this case between the turbulent and mean flow. It is found that more than 95 % of the energy lost by the wave field is dissipated in the first four wave periods after the breaking event. The remaining energy is in the coherent vortex generated by breaking. A scaling argument shows that the ratio between the energy in this breaking generated mean current and the total energy lost from the wave field to the water column due to breaking scales as $(hk)^{1/2}$, where $hk$ is the local slope at breaking. This model is examined using direct numerical simulations of breaking waves solving the full two-phase air–water Navier–Stokes equations, as well as the limited available laboratory data, and good agreement is found for strong breaking waves.

Wave-in-Deck Load Analysis for a Jack-Up Platform

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Thomas E. Schellin ◽  
Milovan Perić ◽  
Ould el Moctar
Keyword(s):  
Stokes Equations ◽  
Wave Theory ◽  
Breaking Waves ◽  
Navier Stokes ◽  
Design Parameters ◽  
Wave Loads ◽  
Wave Direction ◽  
Two Phase ◽  
Highly Nonlinear ◽  
Jack Up

This paper describes the prediction of environmental loads on a typical three-leg jack-up platform under freak wave conditions. Considered were cases where the air gap is small and the hull is subject to impact-related wave-in-deck loads. The technique to predict wave loads was based on the use of a validated CFD code that solves the Reynolds-averaged Navier–Stokes equations. This code relies on the interface-capturing technique of the volume-of-fluid type to account for highly nonlinear wave effects. It computes the two-phase flow of water and air to describe the physics associated with complex free-surface shapes with breaking waves and air trapping, hydrodynamic phenomena that had to be considered to yield reliable predictions. The Stokes fifth-order wave theory initialized volume fractions of water, velocity distributions in the solution domain, and time-dependent boundary conditions at inlet and outlet boundaries. This paper demonstrates that this technique can be a valuable numerical tool for preliminary designs as well as subsequent safety assessments. In particular, it shows that effects of different operating and design parameters on wave-in-deck loads, such as wave direction, wave height, wave period, and wind speed, can be evaluated with an affordable computing effort.

scholarly journals 3-D Oil spill modelling. Natural dispersion and the spreading of oil-water emulsions in the water column

2013 ◽  
Vol 13 (4) ◽  
pp. 325-338 ◽  
Keyword(s):  
Surface Wave ◽  
Water Column ◽  
Oil Spills ◽  
Stokes Equations ◽  
Probability Model ◽  
Breaking Waves ◽  
Navier Stokes ◽  
Two Phase ◽  
Dispersed Oil ◽  
Oil Emulsions

A 3-D hybrid turbulence model, simulating the transport and fate of oil spills in various waters, is used to evaluate the influence of natural dispersion on the spreading of water-in-oil emulsions formed in the water column. The model combines the Navier-Stokes equations for two-phase flows, the RNG k-ε submodel, and parameterized expressions of the basic processes affecting the fate of oil spills. The model also considers the presence of waves, the wind- and wave- induced surface drifts, and the influence of surface wave breaking on the oil spills. Using a stochastic probability model of breaking waves, the loss of surface wave energy into turbulence, due to breaking, is derived and the rate of natural dispersion of oil mass and that of oilwater emulsions formed in the water column is evaluated, under a variety of sea state conditions. Results in the form of oil concentration profiles with depth, graphs showing the variation of the fraction of water (mass) absorbed by the dispersed oil, at various depths and times, as well as graphs showing the oil mass balance, at the sea surface, at various times are compared with counterpart profiles, and graphs obtained from the literature, and useful conclusions are drawn.

CFD Simulations of Spilling Breaking Waves and Steep Waves Past a Monopile Structure at Different KC Numbers

2018 ◽  
Author(s):  
Shengnan Liu ◽  
Muk Chen Ong ◽  
Charlotte Obhrai
Keyword(s):  
Breaking Waves ◽  
Numerical Results ◽  
Navier Stokes ◽  
Wave Forces ◽  
Time Step ◽  
Two Phase ◽  
Secondary Load ◽  
Turbulence Effects ◽  
Sst Turbulence Model ◽  
Steep Waves

A 3D numerical two-phase flow model based on solving Unsteady Reynolds-averaged Navier-Stokes (URANS) equations has been used to simulate spilling breaking waves and steep waves past a monopile structure at a 1:10 slope. The volume of fluid (VOF) method is employed to capture the free surface and the k–ω Shear-Stress Transport (k–ω SST) turbulence model is used to simulate the turbulence effects. Mesh and time-step refinement studies have been conducted. The numerical results of wave forces on the structure are compared with the experimental data from Irschik et al. (2004) to validate the numerical model, and the numerical results are in good agreement with the measured data. The wave forces on the structure at different KC numbers are discussed in terms of the generation of the slamming force. The secondary load cycles are observed after the wave front past the structure. The pressure and velocity distribution, as well as the characteristics of the vortices around the structure at four important instants, are studied.

Numerical Modeling of Evolution of Boundary Between Incompressible Gas and Liquid in Two-Dimensional Region

2006 ◽  
Vol 4 ◽  
pp. 224-236
Author(s):  
A.S. Topolnikov
Keyword(s):  
Numerical Modeling ◽  
Interphase Boundary ◽  
Incompressible Liquid ◽  
Stokes Equations ◽  
Numerical Code ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Incompressible Media ◽  
Good Agreement

The paper is devoted to numerical modeling of Navier–Stokes equations for incompressible media in the case, when there exist gas and liquid inside the rectangular calculation region, which are separated by interphase boundary. The set of equations for incompressible liquid accounting for viscous, gravitational and surface (capillary) forces is solved by finite-difference scheme on the spaced grid, for description of interphase boundary the ideology of Level Set Method is used. By developed numerical code the set of hydrodynamic problems is solved, which describe the motion of two-phase incompressible media with interphase boundary. As a result of numerical simulation the solutions are obtained, which are in good agreement with existing analytical and experimental solutions.

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