A large-eddy-simulation-based numerical wave tank for three-dimensional wave-structure interaction

2021 ◽  
pp. 105179
Author(s):  
Aristos Christou ◽  
Thorsten Stoesser ◽  
Zhihua Xie
Keyword(s):  
Three Dimensional ◽  
Wave Structure ◽  
Numerical Wave Tank ◽  
Structure Interaction ◽  
Eddy Simulation ◽  
Simulation Based ◽  
Large Eddy ◽  
Numerical Wave ◽  
Wave Structure Interaction ◽  
Dimensional Wave

Wave-Structure Interaction of Focussed Waves With REEF3D

2016 ◽  
Author(s):  
Hans Bihs ◽  
Mayilvahanan Alagan Chella ◽  
Arun Kamath ◽  
Øivind A. Arnsten
Keyword(s):  
Free Surface ◽  
Level Set ◽  
Wave Structure ◽  
High Order ◽  
Navier Stokes ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Structure Interaction ◽  
Numerical Wave ◽  
Wave Structure Interaction

For the stability of offshore structures, such as offshore wind foundations, extreme wave conditions need to be taken into account. Waves from extreme events can become critical from design perspective. In a numerical wave tank, extreme waves can be generated through focussed waves. Here, linear waves are generated from a wave spectrum. The wave crests of the generated waves coincide at a pre-selected location and time. In order to test the generated waves, the time series of the free surface elevation are compared with experimental benchmark cases. The numerically simulated free surface shows good agreement with the measurements from experiments. In further computations, the wave impact of the focussed waves on a vertical circular cylinder is investigated. The focussed wave generation is implemented in the numerical wave tank module of REEF3D, which has been extensively and successfully tested for various wave hydrodynamics and wave-structure interaction problems in particular and for free surface flows in general. The open-source CFD code REEF3D solves the three-dimensional Navier-Stokes equations on a staggered Cartesian grid. Solid boundaries are taken into account with the ghost cell immersed boundary method. For the discretization of the convection terms of the momentum equations, the conservative finite difference version of the fifth-order WENO (weighted essentially non-oscillatory) scheme is used. For temporal treatment, the third-order TVD (total variation diminishing) Runge-Kutta scheme is employed. For the pressure, the projection method is used. The free surface flow is solved as two-phase fluid system. For the interface capturing, the level set method is selected. The level set function can be discretized with high-order differencing schemes. This makes it the appropriate solution for wave propagation problems based on Navier-Stokes solvers, which requires high-order numerical methods to avoid artificial wave damping. The numerical model is fully parallelized based on the domain decomposition, using MPI (message passing interface) for internode communication.

scholarly journals Focused waves and wave–structure interaction in a numerical wave tank

2012 ◽  
Vol 45 ◽  
pp. 9-21 ◽  
Author(s):  
J. Westphalen ◽  
D.M. Greaves ◽  
C.J.K. Williams ◽  
A.C. Hunt-Raby ◽  
J. Zang
Keyword(s):  
Wave Structure ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Structure Interaction ◽  
Numerical Wave ◽  
Wave Structure Interaction

Numerical investigation of passive cavitation control using a slot on a three-dimensional hydrofoil

2019 ◽  
Vol 30 (7) ◽  
pp. 3585-3605 ◽  
Author(s):  
Cheng Liu ◽  
Qingdong Yan ◽  
Houston G. Wood
Keyword(s):  
Three Dimensional ◽  
Cavitating Flow ◽  
Control Technique ◽  
Cavitation Model ◽  
Content Type ◽  
Eddy Simulation ◽  
Simulation Based ◽  
Large Eddy ◽  
Flow Turbulence ◽  
Cavitation Behavior

Purpose The purpose of this paper is to study the mechanism and suppression of instabilities induced by cavitating flow around a three-dimensional hydrofoil with a particular focus on cavitation control with a slot. Design/methodology/approach The transient cavitating flow around a Clark-Y hydrofoil was investigated using a transport-equation-based cavitation model and the stress-blended eddy simulation model was used to capture the flow turbulence. A homogeneous Rayleigh–Plesset cavitation model was used to model the transient cavitation process and the results were validated with test data. A slot was applied to the hydrofoil to suppress cavitation instabilities, and various slot widths and exit locations were applied to the blade and the cavitation behavior, as well as drag/lift forces, were simulated and compared to investigate the effects of slot geometries on cavitation suppression. Findings The large eddy simulation based turbulence model was able to capture the interactions between the cavitation and turbulence. Moreover, the simulation revealed that the re-entrant jet was responsible for the periodic shedding of cavities. The results indicated that a slot was able to mitigate or even suppress cavitation-induced instabilities. A jet flow was generated at the slot exit and disturbed the re-entrant jet. If the slot geometry was properly designed, the jet could block the re-entrant jet and suppress the unsteady cavitation behavior. Originality/value This study provides unique insights into the complicated transient cavitation flows around a three-dimensional hydrofoil and introduces an effective passive cavitation control technique useful to researchers and engineers in the areas of fluid dynamics and turbomachinery.

Wave-in-Deck Loads for an Intricate Pile-Supported Pier and Variation With Deck Clearance

2013 ◽  
Author(s):  
Andrew Cornett ◽  
David Anglin ◽  
Trevor Elliott
Keyword(s):  
Water Waves ◽  
Three Dimensional ◽  
Wave Structure ◽  
Physical Modelling ◽  
Interaction Process ◽  
Air Gap ◽  
Scale Model ◽  
Shallow Water Waves ◽  
Structure Interaction ◽  
Wave Structure Interaction

Many deck structures are located at elevations low enough to be impacted by large waves. However, due to the highly complex and impulsive nature of the interactions between wave crests and intricate deck structures, establishing reliable estimates of extreme pressures and forces for use in design remains challenging. In this paper, results from an extensive set of three-dimensional scale model tests conducted to support the design of a large pile-supported pier (or jetty) are presented and discussed. Relationships between maximum wave-in-deck loads and the deck clearance (air gap) are presented and discussed. Results from numerical simulations of the wave-structure interaction process obtained using the three-dimensional CFD software FLOW-3D® are also presented and discussed. Finally, some initial comparisons between the numerical and physical modelling are also included. This paper provides new insights concerning the character and magnitude of the hydrodynamic pressures and loads exerted on intricate pile-supported deck structures due to impact by non-linear shallow-water waves, and the relationships between the hydrodynamic forcing and the deck clearance or air gap.

scholarly journals Investigation of Higher-Harmonic Wave Forces and Ringing Using CFD Simulations

2018 ◽  
Author(s):  
Arun Kamath ◽  
Hans Bihs ◽  
Csaba Pakozdi
Keyword(s):  
Structural Response ◽  
Vertical Cylinder ◽  
Wave Interaction ◽  
Wave Structure ◽  
Higher Order ◽  
Wave Forces ◽  
Numerical Wave Tank ◽  
Cfd Model ◽  
Structure Interaction ◽  
Wave Structure Interaction

Typical offshore structures are designed as tension-leg platforms or gravity based structures with cylindrical substructures. The interaction of waves with the vertical cylinders in high sea states can result in a resonant response called ringing. Here, the frequency of the structural response is close to the natural frequency of the structure itself and leads to large amplitude motions. This is a case of extreme wave loading in high sea states. This understanding of higher-order wave forces in extreme sea states is an essential parameter for obtaining a safe, reliable and economical design of an offshore structure. The study of such higher-order effects needs detailed near-field modelling of the wave-structure interaction and the associated flow phenomena. In such cases, a Computational Fluid Dynamics (CFD) model that can accurately represent the free surface and further the wave-structure interaction problem can provide important insights into the wave hydrodynamics and the structural response. In this paper, the open source CFD model REEF3D is used to simulate wave interaction with a vertical cylinder and the wave forces on the cylinder are calculated. The harmonic components of the wave force are analysed. The model employs higher-order discretisation schemes such as a fifth-order WENO scheme for convection discretisation and a third-order Runge-Kutta scheme for time advancement on a staggered Cartesian grid. The level set method is used to obtain the free surface, providing a sharp interface between air and water. The relaxation method is used to generate and absorb the waves at the two ends of the numerical wave tank. This method provides good quality wave generation and also the wave reflected from the cylinder are absorbed at the wave generation zone. In this way, the generated waves are not affected by the wave interaction process in the numerical wave tank. This is very essential in the studies of higher-order wave interaction problems which are very sensitive to the incident wave characteristics. The numerical results are compared to experimental results for higher-order forces on a vertical cylinder to validate the numerical model.

Sign in / Sign up

Export Citation Format

Share Document