Wide Crest Research Articles

OVERFLOW AND WAVE OVERTOPPING OVER BROAD QUAY WALLS MODELED WITH OPENFOAM

In the framework of the EU Floods Directive, Flanders Hydraulics Research (FHR) is performing flood modeling studies to evaluate the flood risk along the Belgian coast due to extreme storm surges on the North Sea. Thereto, amongst others, the failure behavior of quay walls in the coastal ports must be determined. Computing the landward non-impulsive wave overtopping discharge over a broad quay, in some cases combined with overflow, on which a flood wall can be present at large distance [O (100 m)] from the front edge poses a particular challenge. This matter, to the authors’ knowledge, is not covered in existing literature, e.g. the European Overtopping Manual. It is also not possible to apply the method for reduction of wave overtopping over a wide crest according to Verwaest et al. (2010), since it was developed for breaking waves on a shallow foreshore overtopping a sloping dike, requiring the determination of a run-up level. It is clear that the landward water flow on the quay should be investigated in more detail, as it is characterized by bottom friction and possible inertia due interaction with the flow reflected at the flood wall. To this end, the CFD toolbox OpenFOAM is used to model the final discharges at the landward side of the quay.

Chemical components distribution and morphology of microcapsules of paprika oleoresin by microscopy and spectroscopy

Microencapsulates containing oleoresin of paprika (OP) and blends of soy protein isolate (SPI), maltodextrin (MD) and gum arabic (GA) as wall materials, were analysed to evaluate the components distribution developed during the encapsulation process. Encapsulation efficiency, glass transition temperature, flowability and physical properties were also assessed. Focused ion beam coupled to scanning electron microscopy (FIB-SEM), confocal laser scanning microscopy (CLSM), X-ray dispersion spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) allowed identifying the effects of OP into microcapsules, chemical components distribution, and morphology. In microencapsulated OP, the hollow capsules ranged from 8 to 23% and Tgs (near to 83 °C and 98 °C). The protein concentration on particle surface (18.08%–68.48%) was evaluated by XPS and the surface composition of powders was identified. The best encapsulation efficiency (88.4%) was exhibited by the formulation OP-0.10% SPI-10.45% MD-9.45% GA; the capsules showed the lowest wall thickness and the maximum nitrogen reduction (%) on the particle surface. As a conclusion, OP reduces the presence of hollow capsules and increases the Tg; the soy protein may be responsible for the folds with wide crests on the particle surface, giving a soft and active surface. Although the stability of oleoresin of paprika microencapsulated is associated with the low values of moisture content, aw, and glass transition temperature, the OP on the external surface, could reduce the protective capacity of any wall material.

Development of New Coastal Erosion Management Method using Wave Direction Control System(1); New CeM: Tendency of Coastal Erosion and Measures, and Suggestion of New CeM

The coastal erosion is largely affected either by construction of port/fishery harbor, or coastal road revetment, which of each breaks the balance of longshore sand transport and one of cross-shore sand transport in coast, respectively. The detached type breakwater have been applied to control longshore sand transport as coastal erosion measures against construction of port/fishery harbor which cause longshore sand transport. However, it also produces new coastal erosion near area. Recently, the artificial reef (A.R.) is almost constructed on the standpoint of landscape as coastal erosion measures in Korea. A.R. is a submerged breakwater with wide crest and had developed to overcome weakness on the detached and submerged breakwaters. The wave is turned into strong longshore current passing through A.R., which occasionally results in scouring erosion around the A.R by increasing the water level at the back of A.R. In this study, we examined the coastal erosion occurrence by port/fishery harbor development and tendency of erosion measures. Also, problems of A.R. are examined with review on research and application example. Based on these, this study proposes new coastal erosion management method, ‘New CeM’, for erosion measure in coast where balance of longshore sand transport is broken. Instead of directly protecting against the ingressive wave, the new method is the wave direction control system for correcting the imbalance of longshore sand transport by obliquely installing breakwater of detached type. The performance and physical phenomenon of New CeM will be introduced later.

WAVES OVERTOPPING A WIDE-CRESTED DIKE

If a coastal dike has a crest width of more than say a few meters, then wave overtopping will be significantly reduced due to the crest width, because kinetic energy can be dissipated on the crest and water on the crest can flow back towards the seaside. In coastal towns built on dune belts often a wide-crested coastal dike was constructed as both coastal protection and sea promenade. However, quantifying the effect of such a wide crest on wave overtopping is not straightforward because no empirical overtopping formulas are given in literature for this kind of configuration. Therefore physical scale model research was carried out. Also a simplified theoretical model concept was used based on an energy balance formulation of a single overtopping wave. Combining the scale model measurements with the theoretical model, a semi-empirical formula was developed and calibrated.

Turned Brånemark System® Implants in Wide and Narrow Edentulous Maxillae: A Retrospective Clinical Study

The available jawbone volume is regarded as one of the most important factors when assessing the prognosis of oral implants in the rehabilitation of the edentulous maxilla. The aim of the current investigation was to retrospectively evaluate and compare the outcome of implants placed in edentulous maxillae with either wide or narrow jaw shapes. The marginal bone loss and implant cumulative survival rates (CSRs) were calculated and analyzed with special reference to smoking habits. The study included 75 individuals with edentulous maxillae, of which 33 patients exhibited wide (group A) and 42 patients exhibited narrow jaw shapes (group B). A total of 506 turned Brånemark System (Nobel Biocare AB, Göteborg, Sweden) implants were inserted (226 in group A and 279 in group B) and followed clinically up to 7 years. Smoking habits were recorded. Radiographs were obtained at connection of prostheses, and at the 1- and 5-year follow-up visit. The marginal bone loss was calculated for the groups and analyzed using t-test. Twenty-eight implants were lost during the study period, revealing implant CSRs at 7 years of 94.6% (11/226) and 93.6% (17/279) for wide and narrow crests, respectively. No difference in marginal bone loss was seen between the two groups, although a trend toward more bone loss was recorded for patients with wide crests. Smoking habits were more common in group A (45%) than in group B (31%). During the first year of function, smokers lost significantly more marginal bone than nonsmokers (p = .0447), albeit this difference did not prevail (p > .05) at the end of the study period. The implant CSRs at 7 years were equally good for the two groups of patients with various jaw shapes. Initially, smokers showed significantly more marginal bone loss than nonsmokers.

Irregular Wave Seepage and Overtopping of Permeable Slopes

Experiments were conducted in a wave flume to investigate wave seepage and overtopping of permeable stone slopes with wide crests. The numerical model based on the time-averaged continuity, momentum, and energy equations is extended to include the landward water flux due to wave seepage and overtopping. The measured wave runup distributions are fitted to the Weibull distribution whose shape parameter increases with the increase of the wave overtopping probability. The wave overtopping rate normalized by the wave-induced water flux at the still water shoreline is shown to depend on the wave overtopping probability and the horizontal number of stones above the maximum wave setup. A simple formula for the seepage rate is proposed by analyzing the seepage flow driven by the wave setup on the seaward slope. The extended numerical model is shown to be in agreement with the measurements of the free surface elevation, cross-shore velocity, wave runup, and seepage and overtopping rates but will need to be evaluated using more extensive data sets.

Field Measurement of Ship Waves in Victoria Harbor

Field measurement of ship waves has been carried out in Victoria Harbor of Hong Kong. The wave data were collected at 18 monitoring stations by the underwater pressure/current instrument S4ADW and a floating wave rider TYPE 1156. It is found that the wave conditions in the study area are predominantly affected by the ship-generated waves under normal weather conditions. By comparing with the wind-generated waves in the open region which are irregular but with dominant directional characteristics, the existing harbor–wave field is much more complex. The irregular ship–wave field is not statistically stationary. It is also found that the ship–wave spectra are either of multiple peaks or have wide crests without distinct peaks.