scholarly journals Assessment of Extreme Wave Impact on Coastal Decks with Different Geometries via the Arbitrary Lagrangian-Eulerian Method

2021 ◽  
Author(s):  
Tao Xiang ◽  
Denis Istrati
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Wave Structure ◽  
Arbitrary Lagrangian Eulerian ◽  
Wave Impact ◽  
Arbitrary Lagrangian Eulerian Method ◽  
Wave Heights ◽  
Multi Phase ◽  
Wave Induced ◽  
Uplift Forces

Given the documented wave-induced damage of elevated coastal decks during extreme natural hazards (e.g. hurricanes) in the last two decades, it is of utmost significance to decipher the wave-structure-interaction of complex deck geometries and quantify the associated loads. Therefore, this study focuses on the assessment of solitary wave impact on open-girder decks that allow the air to escape from the sides. To this end, an arbitrary Lagrangian-Eulerian (ALE) numerical method with a multi-phase compressible formulation is used for the development of three-dimensional hydrodynamic models, which are validated against a large-scale experimental dataset of a coastal deck. Using the validated model as a baseline, a parametric investigation of different deck geometries with a varying number of girders Ng and three different widths, was conducted. The results reveal that the Ng of a superstructure has a complex role and that for small wave heights the horizontal and uplift forces increase with the Ng, while for large waves the opposite happens. If the Ng is small the wave particles accelerate after the initial impact on the offshore girder leading to a more violent slamming on the onshore part of the deck and larger pressures and forces, however, if Ng is large then unsynchronized eddies are formed in each chamber, which dissipate energy and apply out-of-phase pressures that result in multiple but weaker impacts on the deck. The decomposition of the total loads into slamming and quasi-static components, reveals surprisingly consistent trends for all the simulated waves, which facilitates the development of predictive load equations. These new equations, which are a function of Ng and are limited by the ratio of the wavelength to the deck width, provide more accurate predictions than existing empirical methods, and are expected to be useful to both engineers and researchers working towards the development of resilient coastal infrastructure.

scholarly journals Assessment of Extreme Wave Impact on Coastal Decks with Different Geometries via the Arbitrary Lagrangian-Eulerian Method

2021 ◽  
Vol 9 (12) ◽  
pp. 1342
Author(s):  
Tao Xiang ◽  
Denis Istrati
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Wave Structure ◽  
Arbitrary Lagrangian Eulerian ◽  
Wave Impact ◽  
Arbitrary Lagrangian Eulerian Method ◽  
Wave Heights ◽  
Multi Phase ◽  
Wave Induced ◽  
Uplift Forces

Given the documented wave-induced damage of elevated coastal decks during extreme natural hazards (e.g., hurricanes) in the last two decades, it is of utmost significance to decipher the wave-structure-interaction of complex deck geometries and quantify the associated loads. Therefore, this study focuses on the assessment of solitary wave impact on open-girder decks that allow the air to escape from the sides. To this end, an arbitrary Lagrangian-Eulerian (ALE) numerical method with a multi-phase compressible formulation is used for the development of three-dimensional hydrodynamic models, which are validated against a large-scale experimental dataset of a coastal deck. Using the validated model as a baseline, a parametric investigation of different deck geometries with a varying number of girders Ng and three different widths, was conducted. The results reveal that the Ng of a superstructure has a complex role and that for small wave heights the horizontal and uplift forces increase with the Ng, while for large waves the opposite happens. If the Ng is small the wave particles accelerate after the initial impact on the offshore girder leading to a more violent slamming on the onshore part of the deck and larger pressures and forces, however, if Ng is large then unsynchronized eddies are formed in each chamber, which dissipate energy and apply out-of-phase pressures that result in multiple but weaker impacts on the deck. The decomposition of the total loads into slamming and quasi-static components, reveals surprisingly consistent trends for all the simulated waves, which facilitates the development of predictive load equations. These new equations, which are a function of Ng and are limited by the ratio of the wavelength to the deck width, provide more accurate predictions than existing empirical methods, and are expected to be useful to both engineers and researchers working towards the development of resilient coastal infrastructure.

Simulation-Based Analysis of 3D Flow Inside a Micropump With Passive Valves

2007 ◽  
Author(s):  
A. F. Tabak ◽  
A. Solak ◽  
E. Y. Erdem ◽  
C. Akcan ◽  
S. Yesilyurt
Keyword(s):  
Flow Rate ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Driving Frequency ◽  
Arbitrary Lagrangian Eulerian ◽  
Navier Stokes Equations ◽  
New Developments ◽  
Arbitrary Lagrangian Eulerian Method ◽  
Simulation Based

It is expected that chemical, biological and environmental applications of microdevices will increase with new developments in micromachining techniques. In this work, a micropump design that utilizes passive valves and an actuated diaphragm is presented. The flow rate is controlled by the deflection and the frequency of the diaphragm’s displacement. Passive valves are used for directing the flow. Poiseuille flow analogy is used to generate the equivalent pressure drop and flow rate via modifying the viscosity in the valve-channel in order to replace the variation of the channel width due to valve movement. Overall flow in the micropump is governed by three-dimensional time-dependent Navier Stokes equations. Deformation of the domain due to moving boundaries that coincide with the diaphragm motion is handled with the arbitrary Lagrangian-Eulerian method. Flow rate, hydraulic power and the efficiency of the micropump are obtained with respect to driving frequency and displacement of the diaphragm.

scholarly journals Experimental Evidence of the Influence of Recurves on Wave Loads at Vertical Seawalls

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 889 ◽  
Author(s):  
Dimitris Stagonas ◽  
Rajendran Ravindar ◽  
Venkatachalam Sriram ◽  
Stefan Schimmels
Keyword(s):  
Large Scale ◽  
Vertical Wall ◽  
Breaking Waves ◽  
Wave Loads ◽  
Incoming Wave ◽  
Wave Heights ◽  
The Mean ◽  
Peak Pressures ◽  
Wave Induced ◽  
Incident Waves

The role of recurves on top of seawalls in reducing overtopping has been previously shown but their influence in the distribution and magnitude of wave-induced pressures and forces on the seawall remains largely unexplored. This paper deals with the effects of different recurve geometries on the loads acting on the vertical wall. Three geometries with different arc lengths, or extremity angles (αe), were investigated in large-scale physical model tests with regular waves, resulting in a range of pulsating (non-breaking waves) to impulsive (breaking waves) conditions at the structure. As the waves hit the seawall, the up-rushing flow is deflected seawards by the recurve and eventually, re-enters the underlying water column and interacts with the next incoming wave. The re-entering water mass is, intuitively, expected to alter the incident waves but it was found that the recurve shape does not affect wave heights significantly. For purely pulsating conditions, the influence of αe on peak pressures and forces was also negligible. In marked contrast, the mean of the maximum impulsive pressure and force peaks increased, even by a factor of more than two, with the extremity angle. While there is no clear relation between the shape of the recurve and the mean peak pressures and forces, interestingly the mean of the 10% highest forces increases gradually with αe and this effect becomes more pronounced with increasing impact intensity.

Green Water and Wave Impact on FPSOs in Santos Basin: Challenges and Prediction Tools

2014 ◽  
Author(s):  
Rafael Vergara Schiller ◽  
Csaba Pâkozdi ◽  
Carl Trygve Stansberg ◽  
Daniel Fonseca de Carvalho e Silva
Keyword(s):  
Wave Structure ◽  
Sensitivity Study ◽  
Irregular Waves ◽  
Green Water ◽  
Wave Impact ◽  
Wave Amplification ◽  
Campos Basin ◽  
Water Problem ◽  
In Transit ◽  
Wave Induced

Green water (water-on-deck) and subsequent wave impact is a strongly non-linear, random and complex phenomenon that represents an important factor to be considered in the design of moored vessels and vessels in transit. The Santos Basin, in southeast Brazil, is a new frontier for deep water oil production, where FPSO green water issues are expected to be more important. In this paper, we investigate new green water challenges associated with the Santos Basin. We employ an engineering prediction tool, KINEMA, designed to predict wave-induced impact loads on FPSOs in steep irregular waves, and for use in early design load analysis. We perform a sensitivity study to arbitrary wave directions and present preliminary results from a case study that would be illustrating for the Santos Basin. Firstly, a comparison between numerical green water predictions and a set of earlier model test data for a Campos Basin case shows satisfactory agreement. A sensitivity study suggests that an empirical tuning factor, which is related to wave amplification and wave-structure interaction, should decrease with increasing wave heading. Then, a preliminary numerical investigation of the green water problem in Santos Basin wave conditions demonstrates that although the wave impact from the largest waves (S-SW) may be avoided by heading the vessel towards S-SW, other wave directions have to be taken into consideration. The results presented herein confirm that multi-directional wave heading is a green water challenge in the Santos Basin. Further studies that address this problem in detail, in special variations in the wave-structure interactions due to wave heading, and for actual particular Santos Basin FPSO’s, are recommended.

scholarly journals Three-dimensional simulation of non-uniform sediment transport based on multi-phase Eulerian approach: Application to debris flow

2018 ◽  
Vol 40 ◽  
pp. 05051
Author(s):  
Kazuyuki Ota ◽  
Hitoshi Suto ◽  
Takahiro Sato
Keyword(s):  
Numerical Model ◽  
Debris Flow ◽  
Large Scale ◽  
Three Dimensional ◽  
Flow Property ◽  
Size Segregation ◽  
Particle Collisions ◽  
Sediment Size ◽  
Dimensional Simulation ◽  
Multi Phase

To simulate 3D flow of a non-uniform and highly concentrated sediment, a numerical model using a multi-phase Eulerian method for air, water, and particles of various class size is developed. This model accounts for turbulence in pore water, particle-particle collisions, and enduring friction. To test its performance, simulations were performed for large scale debris-flow experiments. The numerical model reproduces successfully the flow property and sediment size segregation of the debris flow.

scholarly journals UPLIFT FORCES ON WAVE EXPOSED JETTIES: SCALE COMPARISON AND EFFECT OF VENTING

2012 ◽  
Vol 1 (33) ◽  
pp. 34 ◽  
Author(s):  
Maria Gabriella Gaeta ◽  
Luca Martinelli ◽  
Alberto Lamberti
Keyword(s):  
Large Scale ◽  
Scale Effects ◽  
Time Correlation ◽  
Irregular Waves ◽  
Small Scale ◽  
Static Loads ◽  
Convective Processes ◽  
Wave Celerity ◽  
Wave Induced ◽  
Uplift Forces

The large-scale experiments described herein were carried out at Forschungs-Zentrum Küste (FZK), Hannover (Germany) by a research team composed by the Universities of Bologna, Edinburgh, Southampton, Plymouth and the Coast & Harbor Engineering Inc (USA). Wave-induced loads on close-to-prototype jetties were measured. Experimental evidence indicates the presence of force peaks with a short space-time correlation structure, carried by convective processes with a velocity of the order of the wave celerity. After a 100 Hz sampling, forces on the deck bays and front induced by regular and irregular waves are analyzed, focusing the effects on the wave-in-deck loads of (i) wave irregularity, (ii) air venting and (iii) experiment scale in the evaluation of maximum and quasi-static loads. A comparison with the small-scale results is carried out, but differences could not be directly ascribed to scale effects only.

scholarly journals Evaluate the impact of hydrodynamic pressure on hydrologic exchange fluxes and resident time for a large-scale river section over a long-term period

2021 ◽  
Author(s):  
Jie Bao ◽  
Yunxiang Chen ◽  
Yilin Fang ◽  
Xuehang Song ◽  
William Perkins ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Hydrodynamic Pressure ◽  
Subsurface Water ◽  
Flow Transport ◽  
Resident Time ◽  
Phase Surface ◽  
Hydrologic Exchange ◽  
Multi Phase ◽  
The Impact

Quantifying hydrologic exchange fluxes (HEF) and subsurface water residence times (RT) are important for managing the water quality and ecosystem health in dynamic river corridor systems. Laboratory-scale experiments and models have shown that hydrodynamic pressure variations on the riverbed induced by dynamic river flows can strongly impact HEFs and RTs. In this study, the impacts of hydrodynamic pressure on HEFs and RT for a 30 km section of the Columbia River in Washington State over a three-year period were quantitatively evaluated using a coupled transient three-dimensional (3D) multi-phase surface and subsurface water flow transport approach. Based on comparisons between model simulations with and without considering hydrodynamic pressure, we found that hydrodynamic pressure increase the net HEFs by 7% of flowing into river from subsurface domain, and also leads to a reduction of the area with long RT, and increase of area with short RT.

Wave-Induced Oscillatory Soil Response Around Circular Rubble-Mound Breakwater Head

2017 ◽  
Author(s):  
Dagui Tong ◽  
Chencong Liao ◽  
Jianhua Wang ◽  
Dongsheng Jeng
Keyword(s):  
Pore Pressure ◽  
Numerical Scheme ◽  
Wave Motion ◽  
Three Dimensional ◽  
Wave Structure ◽  
Soil Response ◽  
Seabed Interaction ◽  
Rubble Mound ◽  
Wave Induced

The wave-structure-seabed interaction (WSSI) around circular rubble-mound breakwater head is investigated using a three-dimensional (3D) numerical scheme. The result reveals that the presence of breakwater has strong effect on wave motion and seabed response. The turbulence induced by the breakwater head gives rise to extensive pore pressure around the breakwater head, which could further lead to liquefaction or scour and might eventually result in breakwater failure.

scholarly journals Unstructured Finite-Volume Model of Sediment Scouring Due to Wave Impact on Vertical Seawalls

2021 ◽  
Vol 9 (12) ◽  
pp. 1440
Author(s):  
Miguel Uh Zapata ◽  
Damien Pham Van Bang ◽  
Kim Dan Nguyen
Keyword(s):  
Numerical Modeling ◽  
Finite Volume ◽  
Three Dimensional ◽  
Wave Structure ◽  
Complex Nature ◽  
Breaking Wave ◽  
Computational Domain ◽  
Wave Impact ◽  
Interface Evolution ◽  
Fully Implicit

The numerical modeling of sediment transport under wave impact is challenging because of the complex nature of the triple wave–structure–sediment interaction. This study presents three-dimensional numerical modeling of sediment scouring due to non-breaking wave impact on a vertical seawall. The Navier–Stokes–Exner equations are approximated to calculate the full evolution of flow fields and morphodynamic responses. The bed erosion model is based on the van Rijn formulation with a mass-conservative sand-slide algorithm. The numerical solution is obtained by using a projection method and a fully implicit second-order unstructured finite-volume method in a σ-coordinate computational domain. This coordinate system is employed to accurately represent the free-surface elevation and sediment/water interface evolution. Experimental results of the velocity field, surface wave motion, and scour hole formation hole are used to compare and demonstrate the proposed numerical method’s capabilities to model the seawall scour.

Sign in / Sign up

Export Citation Format

Share Document