Coastal and Maritime Presentations
Download user presentations that focus on coastal and maritime applications using FLOW-3D from past users conferences.
FLOW-3D HYDRO application to marinas
Ignacio Berenguer Pérez, HIDTMA, S.L.
In the late 1970s, wave propagation models based on the Boussinesq equations became operational. The Boussinesq equations approximate the Navier-Stokes equations, in which vertical components of the flow are replaced by horizontal derivatives. As a result, the Boussinesq equations do not have the ability to directly simulate the behavior or account for the effects on the flow of floating structures. However, the behavior can be approximated by including in the model porous structures with a certain wave transmission capacity.
Improvements to CFD models in wave agitation studies make carrying out three-dimensional analysis of wave propagation possible. Three-dimensional models fully resolve the Navier-Stokes equations without approximations or assumptions of the vertical flow components and allow for wave propagation and dissipation to be analyzed without the need for empirical loss coefficients. This provides a complete description of the flow including wave propagation, wave dissipation, and baseline currents while also allowing for the effects of floating structures to be evaluated.
Application cases of CFD technology within maritime engineering include:
- Study of floating docks
- Behavior of floating pontoons
- Agitation studies in installations with floating elements
- Agitation studies in installations protected with screens
Numerical simulations of breaking wave loading on vertical seawalls using FLOW-3D HYDRO and validation
Ramtin Sabeti and Mohammad Heidarzadeh, Department of Civil & Environmental Engineering, Brunel University London
The recent increase in storminess and frequency of extreme coastal waves has highlighted the need for further studies into wave loadings on coastal structures. It is very important to accurately estimate wave loads for the design of coastal structures such as seawalls and breakwaters. In this study, we used FLOW-3D HYDRO to model breaking wave impacts on a vertical concrete seawall. The total forces and pressure distributions along the height of the structure are compared to the experimental data of Cuomo et al. (2010) [Coastal Engineering 57, 424–439]. The entire flow domain is 3.0 m wide, 0.40 m deep and 100 m long, consistent with Cuomo et al. (2010). To reproduce the irregular waves, the left surface of the domain is inputted with a random wave and set as the JONSWAP wave spectrum with a peak enhancement factor of 3.3, consistent with the conducted physical experiments. The Courant number is used to ensure the stability of the numerical calculations and to evaluate the suitability of the time-stepping procedure. The validated model will be used for developing the predictive equations to estimate the impact forces of random waves on vertical seawalls.
Analysis of the hydrodynamic behavior platform to support wind generators in deep water
Ignacio Berenguer Pérez, HIDTMA,S.L. and Ignacio Cobian Babé, BERIDI, S.L.
The construction of the platform is based on the construction technique of floating caissons. The main advantage of the designed platform is that it allows the construction and complete assembly of the platform/turbine system in protected areas and its subsequent transfer to the installation area, as a floating body where only anchoring is necessary. Studies have been carried out using FLOW-3D to perform a complete analysis of fluid-structure interaction to obtain the resulting forces, stresses, and strains on bodies. The CFD studies carried out are an essential component to reduce the total effort required in the laboratory, whose main objectives in our case were the following:
- To obtain a calibration model using the results of a physical model study carried out by IHCantabria
- To determine the optimal size of cells and holes
- To determine the optimal size of the holes’ diameter
- To determine the optimal size of the heave plate
- To determine the natural periods of heave and pitch
- To verify the amplitudes of movement in the waves of a period similar to the natural ones of the platform
- To determine the pressures on the walls
Numerical and experimental investigation of scour development caused by ship propeller
Cansu Özyaman and Selim Altun, Ege University, Civil Engineering Department, Mustafa Doğan, Dokuz Eylül University, Civil Engineering Department
Scouring processes due to ship propellers can generate several problems in harbors. Eroded bed due to propeller jets causes problems for the stability of dock foundations and reduces the total depth of the harbor basin and navigation channel. Scouring also causes pollution through resuspension of contaminants that had settled at the harbor bed. To gain a better understanding of the propeller jet effect on marine environments, the water jet formed by a propeller and time- dependent scouring on the seabed were investigated numerically and experimentally. Experiments were conducted in a rectangular pool located at the Ege University Civil Engineering Department. The model propeller was a Wageningen B series propeller with a diameter of 6 cm corresponding to a 1.2 m propeller in the prototype. Experiments were conducted at different propeller speeds (500 rpm, 750 rpm). The numerical model was performed using FLOW-3D. Since the results of the RNG model simulations have better agreement with experimental results, the RNG turbulence model was chosen for the simulations in this study. The sediment scour model was activated. Fine sand with a mean grain size of 0.25 mm and a density of 2650 kg/m3 was used. Five surfaces of the experiment pool are defined as wall boundary conditions and the upper surface is defined as a pressure boundary condition. The STL model of the Wageningen B series propeller was imported to FLOW-3D and defined as a moving object. However, because of the extreme simulation time and storage requirements, the impeller model was chosen to simulate the propeller. The impeller model induces both rotational and axial velocity components. After defining impeller properties such as rotation speed and radius, different rotational (𝐴𝐴𝐴𝐴) and axial velocity coefficients (𝐵𝐵𝐴𝐴) were selected to achieve the experiment results. The efflux velocity of the impeller was compared with the experiment measurements taken by an Acoustic Doppler Velocimeter (ADV), thus axial velocity coefficient (𝐵𝐵𝐴𝐴) was decided. The efflux velocity was redefined considering efflux velocities (ADV) and velocities taken from FLOW-3D. Time-dependent scour depths were given and compared.
Observations of experiments and simulations have shown that scour depth increases with time and then it remains almost constant after 150 minutes. The experimental results of time dependent scour depths are in good agreement with numerical results.
Levelling system new shipping lock IJmuiden, the Netherlands
Jeroen Adema, Arcadis Netherlands, John Richardson and Randy Lagumbay, Arcadis USA
This presentation was given at both the 17th FLOW-3D European Users Conference and the 2017 FLOW-3D Americas Users Conference.
Arcadis is one of the consultants within the consortium OpenIJ that is building the new shipping lock in IJmuiden for the Dutch Ministry of Public Works. This lock, the biggest in the world, will improve the connection between the port of Amsterdam and the North Sea. The most crucial topic in terms of design was to show that the levelling system could meet the requirements on levelling times and forces on a moored ship. First, three validation cases were carried out to show the reliability of FLOW-3D, before we could start to model the levelling system. Grid sizes as small as 1 cm were required to model the geometry of the levelling system in enough detail to obtain reliable values for the discharge coefficient. Flow patterns were evaluated on the spreading of the high velocity zones downstream, which led to a design optimization of the breaking bar geometry. Energy losses and discharge coefficients were input to determine lift gate operations with the 1D model Lockfill. Physical scale model tests in the lab were used for the final check of the levelling times and forces on the ship. Discharge coefficients from FLOW-3D compared well with those of the scale model.
Cyclone wave loads on wharf structure using the New-wave approach
Trevor Elliott and Michael Fullarton; W.F. Baird & Associates
A three-dimensional numerical model was developed of a pile-supported wharf structure for a new iron ore marine loading facility in Western Australia. FLOW-3D was used in this study to support a scoping assessment to investigate the model’s ability to generate extreme waves in shallow water and predict wave-in-deck loads on the wharf structure.
The generation of extreme waves in shallow water can be problematic for numerical models due to non-linearities and breaking in these highly dynamic and complex conditions. The CFD model was essential for the simulation of wave-structure interactions, free-surface breakup/fluid splashing, and the computation of localized impact pressures and global forces on structural members of the wharf deck.
Wave generation in the numerical model used the New-wave approach (Tromans et al., 1991) so that the most probable extreme wave is obtained immediately. This feature was essential considering that running 3-hour sea states was not feasible in the CFD model. The use of the New wave model for design wave conditions is an attractive alternative to more traditional non-linear periodic wave theories (e.g. Stokes/Stream-function theories) where, as noted by Tromans et al., application of the new wave model to fluid load assessments offers the realism of time domain simulations with the speed and convenience of a deterministic analysis.
Application of FLOW-3D to tsunami analyses
Osamu Kiyomiya1 and Yasunori Nemoto2
2Flow Science Japan, Ltd.
A plate-boundary thrust earthquake at the Japan Trench of magnitude 9.0 occurred at March 11, 2011, with its epicenter located in the Pacific Ocean off the Japan coast. The quake caused immense tsunami damage in coast areas. The observed height of the tsunami was 7-10m. Damage occurred over a wide area, and all facilities located within the coastal area suffered damage. To study the causes of these damage and establishment of the counter measures, various analyses have been carried out. This presentation outlines the tsunami and damage of the structures in the Pacific Ocean off the Japan Coast in 2011.
Application of FLOW-3D for tsunami analysis started about 10 years ago and validity of the tsunami estimation has been done by comparing simulation results to experiment results. FLOW-3D is widely applicable for various problems about the tsunami. Estimation of wave height and wave velocity of tsunami is important to know potential damaged area, to establish evacuation plans, etc. Estimation of wave force is also necessary for stability design of the structures. Analysis of drift materials and ships estimate safety of the human beings and the structures during tsunami.
This presentation shows several simulation results about the tsunami analysis as case studies. (1) Overflow simulation of the bank and the wall: The tsunami overflowed the bank and the concrete wall. By simulation, velocity and height of the tsunami were estimate to damage of the facilities and scored area. (2) Run up analysis of small port: run-up area and tsunami height were estimated to know the counter measure. (3)Tsunami simulation for model test: Simulation was carried out to know the validity of the FLOW-3D analysis for flume model test.
Numerical and physical model test of pile supported slit wall breakwater
Kwang-Oh Ko1, Chang-Beom Park1, Yonguk Ryu1 and Sung-Bum Yoon2
1Hyundai Institute of Construction Technology
2Hanyang University, Dept. of Civil & Environ. Eng.
The pile-supported slit wall breakwater was devised to dissipate the surface wave and to transmit the undersea current. Hence, the tidal current power generator can be installed among piles to produce the electricity by the interaction of the flow and current turbine and the water turbine can be installed inside the perforated wall to make the wave-induced flow power generation. For the application of the internal wave-maker scheme in the FLOW-3D model, two types of perforated wall are considered to compare the results of the simulations with those of the physical model tests. The numerical simulation was carried out with the internal wave maker in the FLOW-3D model on the basis of the linear wave theory.
The physical model tests were carried out to verify the application of an internal wave-maker in the FLOW-3D model with the pile-supported slit wall breakwater. Two dimensional laboratory experiments have been carried out in the wave flume with the width of 1.4 m, the height of 1.5m, and the length of 40m. In the physical model tests, the wave heights in the wave chambers were measured to investigate the reduction ratio of wave height in accordance with various slit wall shapes and several wave conditions. The achieved results from the physical model tests were compared with those of the numerical simulations to check the appropriateness of the internal generation of wave in the FLOW-3D model. In the view of wave power generation, the regular variation of free elevations at the last chamber is the most important thing to produce the regular generation of electricity. From the comparisons, the numerical test results of free surface elevation at the last chamber showed good agreement with those of the physical model tests. Hence, it is regarded that the applicability of the internal wave-maker in FLOW-3D model is verified with the sufficient accuracy.