Relative Run-up Research Articles

Моделирование положения гусеничных шасси в движении при отклонении механических характеристик электродвигателей раздельного привода гусеничных контуров

Deviation of the mechanical characteristics of electric motors from the nominal values during their simultaneous operation in the structure of multi-motor drives can destabilize the accuracy of predicting the behavior of the entire mechanical system. The use of electric motors in the structure of a separate drive of the tracked chassis circuits with a random combination of deviations of their sliding can both enhance the factors contributing to the relative run-up of the circuits and compensate for them depending on the function of the change in the motion resistance coefficient over time. This article provides a description of the process and results of modeling the position of the tracked chassis in motion when the mechanical characteristics of the electric motors of the separate drive of the tracked circuits deviate. The proposed mathematical model, on the one hand, takes into account the possibility of changing the coefficient of resistance to movement over time, and on the other hand, it operates with a variable approach to determining the speed of movement of tracked circuits based on a system of sliding deviations of electric motors. Taking into account the results obtained, recommendations were proposed for the selection of electric motors for the circuits of tracked chassis.

Numerical investigation of wave run-up and load on heaving cylinder subjected to regular waves

The heaving cylinder is widely used in various floating structures, and the wave run-up height and wave forces are essential parameters to be considered in the design. This paper uses OpenFOAM to numerically simulate the wave run-up and wave load of the heaving cylinder by solving the Reynolds-averaged Navier-Stokes equation. The wave run-up of the heaving cylinder is decomposed into the relative run-up height and the absolute run-up height compared with the fixed cylinder, in which the phase difference between the absolute wave run-up curve and the cylindrical motion curve is the important factor. The different wave conditions are considered, including the short wave, resonance wave and long wave. The results show that the dimensionless maximum run-up height of the heaving cylinder changes nonlinearly with the incident wave frequency. In the range of about 23% of the resonance frequency of the heaving cylinder, the increase of the relative run-up height should be considered with the reason of resonance and phase differences. The dimensionless horizontal wave force increases nonlinearly with the increased scattering parameters. The fixed and heaving cylinder results differ significantly from the theoretical value when the ka value is larger than 0.25.

Numerical Analysis of Velocity Magnitude on Wave Energy Converter System in Perforated Breakwater

Waves are an alternative energy source that can be used for electricity generation. Wave Energy Converter (WEC) system in perforated breakwater is potentially applicable WEC system for coastal area. The magnitude of wave energy generated is determined by the volume of sea water inside the perforated breakwater. This volumetric flow rate is calculated using the flow velocity at perforated holes on the structure slope. Therefore, this research aims to study the velocity magnitude by analyzing the interrelation among wave steepness, wave run-up and relative velocity. The method used consists of applying numeric 3D flow model in the perforated structure of the breakwater with the variation of wave height, wave period and structure slope. The result shows that, the steeper the structure, the bigger is the relative run up (Ru/H). The higher the relative run up, the higher are the relative run-up velocities (V/Vru). As the velocity increase, the volumetric flow rate inside perforated breakwater will be higher, which leads to higher wave energy. Hence, it can be concluded that the higher the velocities (V/Vru), the higher is the wave energy generated.

Wave run-up prediction for composite bucket foundation due to regular wave and current

The prediction of wave run-up is a major issue when designing offshore structures, such as offshore wind turbine foundation. In this study M5ʹ model tree algorithm was used to predict the wave run-up for CBF due to regular wave and current. This study investigated wave-only and wave–current run-up on a CBF via model tests. The influences of the relative wave height, wave steepness, and Froude number on the relative run-up were investigated. Based on different combinations of non-dimensional parameters, the performance of novel formulae developed using the M5ʹ model tree (M5MT) algorithm was analysed in terms of statistical error indexes. The relative wave run-up was found to increase with the wave steepness, and under low water depth increase with the Froude number for low wave steepness. Based on the scatter parameter, relative water depth, the prediction formulae developed exhibited optimal performance when predicting run-up under wave-only conditions. New formulae with a reliable precision were developed for wave–current conditions based on the scatter parameter, wave steepness, relative wave height, and Froude number. The experimental results and proposed run-up formulae will assist engineers in the design of CBFs.

Wave Hydrodynamic Characteristics of Vertical and Sloped Seawalls

The hydrodynamic performance of vertical and sloped plane, rectangular serrated, and triangular serrated seawalls were investigated experimentally in terms of wave reflection coefficient, kr, relative wave run-up, Rup/Hi, and relative wave run-down, Rdown/Hi, using physical model studies. Regular waves of wide rang of heights, and periods were used. Tests were carried out for different inclinations of seawall (i.e. ), relative dissipater blocks spacing (s/w =1.0, 2.0, 3.0), and a constant water depth of 0.4 m. It was observed that the rectangular serrated seawall was superior to the triangular serrated and plane seawall in reducing the hydrodynamic parameters mentioned above. As well it was found that the relative spacing of dissipater blocks, s/w, wave steepness, Hi/Li, and the relative water depth, d/Li were better influencing parameters compared to the surf similarity parameter (Iribarren N0), in predicting the wave hydrodynamic parameters. Both rectangular and triangular serrated seawalls gives a good results for all hydrodynamic parameters when, s/w=2.0 compared to s/w equal to1.0 and 3.0. A total performance evaluation was done in terms of a single parameter called hydrodynamic performance parameter, and it was found that for s/w=2.0, both rectangular and triangular serrations reduces this parameter by about 37% and 28% respectively compared with the plane seawall. The worst results for performance parameter were observed when , while the optimum values occur when, s/w equal to (2.21-2.27), and (2.34-2.41) for the rectangular and triangular serrated seawalls respectively. Simple predictive equations were developed for estimating the wave reflection coefficients, relative run-up, and relative run-down by using non-linear regression analysis by SPSS.16 (SPSS Inc, 2006) software.

Effect of wave steepness to relative wave run-up on OWEC breakwater

OWEC (Overtopping Wave Energy Converter) breakwater is a coastal structure model concept. The concept is to integrate the breakwater and the overtopping wave energy converter. This coastal protection model concept is equipped with a reservoir at the top of the structure to collect water that overflows from the top of the structure (overtopping). Many factors influence the amount of wave overtopping discharge; one of them is the run-up height. The height of wave run-up that occurs is influenced by many factors, one of which is the steepness of the incoming wave. The effect of the wave steepness to the relative wave run-up on OWEC breakwater is investigated experimentally. The study is carried out in wave flume with regular waves. The OWEC breakwater model is simulated with slope variations and freeboard variations. The results of the study show that small wave steepness value produces a large relative wave run-up value and vice versa. For a review of the structure slope, the results showed that the largest relative run-up value was obtained in the largest slope of the variation of the slope studied, namely 1: 2, at all different freeboard heights.

Numerical investigation of the solitary wave breaking over a slope by using the finite particle method

Predicting the propagation and transformation of the solitary wave is very important in coastal engineering. This paper presents a numerical investigation of the solitary wave breaking over a slope by using a finite particle method (FPM), which is an enhanced smoothed particle hydrodynamics (SPH). We firstly conduct a comparative study on SPH and FPM in modelling solitary wave and it is demonstrated that FPM performs better than SPH qualitatively and quantitatively. A modified particle shifting technique (PST) is integrated into FPM to avoid possible ill corrective matrix due to extremely disordered particle distribution. We find that the artificial viscous coefficient can greatly influence the wave run-up and propose an empirical equation to quickly determine the optimal value of the artificial viscous coefficient used in the FPM simulations. The solitary wave breaking is then modelled for scenarios with relative wave heights and slopes, and three typical breaking types, including surging breaker (SU), plunging breaker (PL) and spilling breaker (SP), are analyzed. The result indicates that SP affects the pressure field more extensive than PL and SU. When the breaker type transits from SP to SU, the breaker tends to break at a narrower region close to the shoreline, the breaking depth decreases, the breaking index gradually turns into an unstable value, and the relative run-up height of breaking waves becomes larger. Although the wave celerity at breaking has no clear relationship with breaker types, the wave celerity at breaking increases with the increase of the relative wave height and slightly decreases with a steeper slope.

Comparing methods for computation of run-up heights of landslide-generated tsunami in the Northern Sicily continental margin

The North Sicily continental margin is a very active region located in the Central Mediterranean. Strong seismicity, active tectonics and volcanism, fluid escape, high sediment supply, and widespread mass movements historically have exposed this region to marine geohazards, with a potential for tsunami generation. Morpho-bathymetric analysis revealed that one of the most common mechanisms associated with marine geohazards is due to submarine mass failure processes, genetically linked to the other processes active in this margin. With the aim to assess the risks associated with landslide-generated anomalous waves, we selected two sectors of this margin, Gulf of Palermo to the west and Patti offshore to the east. The workflow included analysis of the morpho-bathymetric data, morphometric characterization, calculation of parameters of landslide-generated waves, and computation of run-ups by using different algorithms. Assuming that each of the identified landslides could be a potential tsunamigenic source, we calculated the associated theoretical run-ups, referring to the main computation methodologies proposed in the scientific literature. In order to identify the methodology that better suits run-up values for landslide-generated tsunami, we compared the known run-up values of actual, historical cases with those calculated through the different methodologies. The values obtained with the most suitable equation, both for theoretical and historical events, fit a curve that we used to formulate an empirical law describing the relationships between amplitude and depth, at the source point, and relative run-up. It can be used to calculate easily and promptly the run-up associated with a generic landslide-generated tsunami.

Pneumatic long-wave generation of tsunami-length waveforms and their runup

An experimental study is conducted using a pneumatic long-wave generator (also known as a Tsunami Generator). Scaled tsunami waveforms are produced with periods in the range of 5–230 s and wave amplitudes between 0.03 and 0.14 m in water depths of 0.7–1.0 m. Using Froude similitude in scaling, at scale 1:50, these laboratory waves are theoretically dynamically equivalent to prototype tsunami waveforms with periods between 1 and 27 min and positive wave amplitude between 1.5 and 7.0 m in water depths of 50 m. The purpose of these tests is to demonstrate that the pneumatic method can generate long waves in relatively short flumes and to investigate their runup. Standard wave parameters, (free-surface, wave celerity and velocity profiles) are used to characterise the waveforms. It is shown that for the purpose of runup and onshore ingression, minimal interference from the re-reflected waves is observed.By generating tsunami waveforms with periods greater than ≈ 80 s (≈9.5 mins prototype scale) the available experimental data set is expanded and used to develop a new runup equation. Contrary to the shorter waves, shoaling of these longer waves is insignificant. For waveforms with periods greater ≈ 100 s the runup is best described by wave steepness not potential energy. When tested against available runup equations the results are mixed; most perform poorly for scaled tsunami length periods. A segmented regression analysis is performed on the data set and an empirical runup relationship is provided based on a new parameter termed the ‘Relative Slope Length’.The tests show the definition of offshore wave amplitude is non-trivial and may greatly affect the predicted relative runup of a given wave. It is noted that this appears to be a general issue for all types of tsunami simulation in the laboratory. Together these observations and proposed runup model provide a framework for future numerical studies of the topic.

Wave run-up and rundown on ACB Mats under granular and geotextile filters’ condition

ABSTRACTArticulated concrete block mattress revetment (ACB Mats) is an appropriate revetment for shore protection and breakwater. ACB Mats act as an integrated and flexible revetment against waves. There is a necessary need of investigation due to the lack of exact ACB Mat design relations in the estimation of hydrodynamic processes including wave run-up and run-down parameters. In the present study, using proper laboratory equipment, run-up and run-down processes were investigated under irregular waves and also granular and geotextile filters’ conditions. In this study, wave run-up and run-down estimation relations in ACB Mat revetment with the open area were explored for the first time. As the obtained results showed, relative maximum wave run-up and rundown are desirable for all conditions. Using a geotextile layer under ABC Mat caused a 14% increase in relative wave run-up values compared to granular filter. Further, in the run-down process, geotextile filter caused a 40% decrease in relative wave run-down values. The intensive decrease in run-down value occurred due to the outflow rate of the water from inside the filter with delay during water attack toward downward, which can be effective on structure stability significantly and should be considered in designs.

A novelty coastal susceptibility assessment method: application to Valdelagrana area (SW Spain)

The main aim of this paper is to present a new methodology to determine coastal susceptibility to erosion and flooding processes by means of an index-based method. The proposed indices take into account physical parameters, such as dune and beach geomorphologic characteristics, shoreline evolution, local significant wave height and relative run-up. The coastal susceptibility has been estimated by elaboration of spatial input data into a GIS environment. The method has been tested in Valdelagrana area, a sandy spit located in SW Spain. The spit includes several morpho-sedimentary environments: sandy beach, discontinuous embryo dunes and foredunes, mud flats and wide areas of vegetated salt marshes. The Northernmost sector is densely urbanized whilst the rest is part of a natural protected area belonging to the Bahia de Cadiz Natural Park. The results obtained showed how the Southern part of the spit presented a high susceptibility due to an elevated erosion rate and the presence of low and discontinuous dune ridges.

Nonlinear run-ups of regular waves on sloping structures

Abstract. For coastal risk mapping, it is extremely important to accurately predict wave run-ups since they influence overtopping calculations; however, nonlinear run-ups of regular waves on sloping structures are still not accurately modeled. We report the development of a high-order numerical model for regular waves based on the second-order nonlinear Boussinesq equations (BEs) derived by Wei et al. (1995). We calculated 160 cases of wave run-ups of nonlinear regular waves over various slope structures. Laboratory experiments were conducted in a wave flume for regular waves propagating over three plane slopes: tan α =1/5, 1/4, and 1/3. The numerical results, laboratory observations, as well as previous datasets were in good agreement. We have also proposed an empirical formula of the relative run-up in terms of two parameters: the Iribarren number ξ and sloping structures tan α. The prediction capability of the proposed formula was tested using previous data covering the range ξ ≤ 3 and 1/5 ≤ tan α ≤ 1/2 and found to be acceptable. Our study serves as a stepping stone to investigate run-up predictions for irregular waves and more complex geometries of coastal structures.

Run-up, run-down and reflection characteristics of semicircular breakwater for varying seaside perforations

Breakwaters are mainly used for the purpose of withstanding and dissipating the dynamic energy of ocean waves and thereby provide tranquillity conditions on the lee side. Semicircular breakwaters are being used increasingly around the globe because of their great advantages. The paper explains physical studies conducted on seaside-perforated semicircular breakwater models to evaluate the wave run-up, wave run-down, and reflection coefficient for various wave heights (H), wave periods (T), water depths (d), incident wave steepness (H i/gT 2), depth parameter (d/gT 2), and relative spacing S/D (S = c/c spacing of perforations, D = diameter of perforations) on the seaside. It is observed that as the incident wave steepness increases, there is a decrease in the reflection coefficient (K r), and relative run-down (R d/H i) but increase in relative run-up (R u/H i). As the S/D ratio decreased (percentage of perforations increased), there was drop in the reflection coefficient, relative run-up, and relative run-down. As the depth parameter increased, there was a decrease in the relative run-up and reflection coefficient, but increase in relative run-down.

HYDRODYNAMIC PERFORMANCE CHARACTERISTICS OF SEMICIRCULAR BREAKWATER—WAVE RUN-UP AND RUN-DOWN

ABSTRACT Breakwaters are structures protecting a shore area, harbor, anchorage, or a basin from the fury of ocean waves. They create calm waters and give protection for safe mooring, operating and handling of ships, and provide protection to harbor facilities. Semicircular breakwaters are becoming increasingly popular these days, as they have high stability against the action of waves. The paper explains the physical model studies to evaluate the wave run-up (Rd/Hi) and wave run-down (Rd/Hi) on semicircular breakwater model for various incident wave heights H, wave periods T, water depths d and spacing (S) to diameter (D) ratios of perforations (S/D). It is found that relative wave run-up increases with the increase in wave steepness (Hi/gT2) and relative run-down decreases with the increase in wave steepness. Relative wave run-up and wave run-down values increase with the increase in depth parameter (d/gT2). The relative run-up and run-down values decrease with increasing perforations (decreasing S/D values) in breakwater.

Stability Aspects of Nonreshaped Berm Breakwaters with Reduced Armor Weight

The present work involves the investigation of the influence of wave height, wave period, water depth, and sea-ward slope on the stability, wave runup, and wave rundown of statically stable rubble-mound berm breakwater. The weight of armor stones used in the present study is 20% lighter than the weight that is required for a conventional breakwater, designed using Hudson formula for a wave height of 0.1 m in the model. In the present work models with a berm width of 0.6 m, at constant depth of 0.32 m from the seabed were tested. The damage to the breakwater model with the berm was compared with the results on a model without the berm using different armor weights. The variation of relative runup and rundown was found for different values of wave steepness and water depths in front of the structure. The damage to the breakwater, wave runup, and rundown for the structure with seaward slope 1:2 and 1:1.5 were compared. The investigation was carried out in the Marine Structures Laboratory, Department of Applied Mechanics and Hydraulics, National Institute of Technology Karnataka, Surathkal.

Run-up from impact tsunami

We report on calculations of the on-shore run-up of waves that might be generated by the impact of subkilometre asteroids into the deep ocean. The calculations were done with the COULWAVE code, which models the propagation and shore-interaction of non-linear moderate- to long-wavelength waves (kh < π) using the extended Boussinesq approximation. We carried out run-up calculations for several different situations: (1) laboratory-scale monochromatic wave trains onto simple slopes; (2) 10–100 m monochromatic wave trains onto simple slopes; (3) 10–100 m monochromatic wave trains onto a compound slope representing a typical bathymetric profile of the Pacific coast of North America; (4) time-variable scaled trains generated by the collapse of an impact cavity in deep water onto simple slopes and (5) full-amplitude trains onto the Pacific coast profile. For the last case, we also investigated the effects of bottom friction on the run-up. For all cases, we compare our results with the so-called ‘Irribaren scaling’: The relative run-up R/H0 = ξ = s(H0/L0)−1/2, where the run-up is R, H0 is the deep-water waveheight, L0 is the deep-water wavelength, s is the slope and ξ is a dimensionless quantity known as the Irribaren number. Our results suggest that Irribaren scaling breaks down for shallow slopes s ≤ 0.01 when ξ < 0.1 − 0.2, below which R/H0 is approximately constant. This regime corresponds to steep waves and very shallow slopes, which are the most relevant for impact tsunami, but also the most difficult to access experimentally.

Empirical parameterization of setup, swash, and runup

Using shoreline water-level time series collected during 10 dynamically diverse field experiments, an empirical parameterization for extreme runup, defined by the 2% exceedence value, has been developed for use on natural beaches over a wide range of conditions. Runup, the height of discrete water-level maxima, depends on two dynamically different processes; time-averaged wave setup and total swash excursion, each of which is parameterized separately. Setup at the shoreline was best parameterized using a dimensional form of the more common Iribarren-based setup expression that includes foreshore beach slope, offshore wave height, and deep-water wavelength. Significant swash can be decomposed into the incident and infragravity frequency bands. Incident swash is also best parameterized using a dimensional form of the Iribarren-based expression. Infragravity swash is best modeled dimensionally using offshore wave height and wavelength and shows no statistically significant linear dependence on either foreshore or surf-zone slope. On infragravity-dominated dissipative beaches, the magnitudes of both setup and swash, modeling both incident and infragravity frequency components together, are dependent only on offshore wave height and wavelength. Statistics of predicted runup averaged over all sites indicate a − 17 cm bias and an rms error of 38 cm: the mean observed runup elevation for all experiments was 144 cm. On intermediate and reflective beaches with complex foreshore topography, the use of an alongshore-averaged beach slope in practical applications of the runup parameterization may result in a relative runup error equal to 51% of the fractional variability between the measured and the averaged slope.

Wave Reflection, Run-Up, Run-Down and Pressures on Plane, Dentated and Serrated Seawalls

Experimental investigations on wave reflections, run-up and run-down and wave pressures on plane, dentated and serrated seawalls were carried out for a wide range of wave heights, wave periods, seawall slopes and in a constant water depth of 0.7 m. Based on the measurements, predictive equations are proposed. A total performance evaluation is carried out on each seawall. The improved performance of the serrated seawall compared to plane seawall is brought out. It is found that closer to deep water condition, the reflection coefficients from the serrated and the dentated vertical seawalls are only about 0.5 and 0.6 respectively compared to the fully reflecting plane vertical wall. Sloped serrated seawall is capable of dissipating the wave energy almost two times that of the sloped plane seawall. Closer to still water level, the normalized wave pressure value (ratio of maximum wave pressure to static pressure due to the water column equal to incident wave height) for 2% exceedence is 0.9, 1.1 and 1.15 for the serrated, dentated and plane seawalls. The measured relative run-up value (ratio between the maximum run up to the incident wave height) for 2% exceedence is 1.30, 1.5 and 1.6 for serrated, dentated and plane seawall respectively. Hence, the design crest level of the serrated seawall can be at a lower level than that of the plane seawall. Overall, it is found that the serrated seawall is about 20% to 40% better than the plane seawall for reducing the wave pressure, reflection, run-up and rundown. The results can be used for better hydrodynamic design of coastal structures with vertical face (like quay walls in harbors, vertical seawalls and caisson type breakwaters) and sloped structures (like seawalls, dikes, sea side sloped caissons).

Downrush flow from waves on sloping seawalls

This paper investigates the characteristics of downrush flow from breaking waves on sloping seawalls, which cause toe scour. Flow visualization techniques were employed in these experiments. The velocity and pressure of the downrush flow at the toe were analyzed. It was found that the intensity of the flow is reduced as the structure slope decreases. The empirical formula for normalized flow intensity at the structure toe is presented as a function of the relative wave run-up height.

An experimental study of wave runup on steep curvilinear slopes

A study of the wave runup phenomenon on smooth impermeable curvilinear slopes is conducted in order to investigate the effects of various wave parameters and slope characteristics on the runup and wave reflection. Three arbitrary models with different curvature of each circular, elliptical, hyperbolic and parabolic curves are tested with regular nonbreaking waves. An empirical equation is proposed to express the relative runup with nonlinearity. It is found that the relative runup varies with wave steepness, relative depth and relative height.