cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.4121/uuid:2447c7ea-3c3f-4e70-a7cb-08f217cfa968
title: The notional permeability of breakwaters: experimental research on the permeability factor P

description: The coefficient in the Van der Meer formula, described as the Notional Permeability P, has been determined for three different types of structures. A homogeneous structure, a structure with a permeable core and an impermeable structure. In practice structures are being build who deviate from these standard situations. Therefore there is a demand for values of P about structures other than the known standard situations. In this thesis P values are found by means of physical scale model tests. First of all two reference structures were tested. The permeable and the impermeable structure with known values of P= 0.5 and respectively P=0.1. The values found in this study are almost equal to the values above. The new structure has an impermeable core covered with a thick filter layer. On top of that an under layer is placed and finally there is a double armour layer.
DOI: 10.4121/uuid:270c7967-5242-4329-9b07-a73faec02b20
title: Hydraulic properties of PUR-revetments compared to those of open stone asphalt revetments

description: Elastocoast is a special elastomeric polyurethane system made by Elastogran. It binds broken rocks or stones together to form a stable material which is not only solid but also elastic so that it is able to be an ideal material for hydraulic applications. As a new developed material for revetment, the performance of Elastocoast in the application of revetments is still unknown. This research is carried out to study the feasibility of the Elasatocoast's applications as revetments. Due to the similarities between Elastocoast and open stone asphalt, most of the experiments are done according to the concerning problems of the open stone asphalt revetments. Five properties were tested: porosity, permeability between the material and geotextile, wave run-up, stability on slope and resistance to erosion. It turned out that compared to open stone asphalt Elastocoast is a strong and permeable material and it is relatively easy to construct and maintain. It is expected to be a suitable material as revetment.
DOI: 10.4121/uuid:496d8244-5449-4036-b32f-3bf97f298689
title: Stability of a single top layer of cubes

description: All conclusions in this thesis have been based on model tests, in which the cubes were placed by hand and placed in a stretching bond (half-steensverband). In total eighteen tests were performed in the wave flume of the Fluid Mechanics Laboratory of the Faculty of Civil Engineering and Geosciences. Two different slopes were tested together with three different packing densities and three different wave steepness. It was found that the gentler slope did not contribute to the stability in this setting using a stretching bond. In fact the model failed earlier than the model with a steeper slope in most cases. The best results were found using a slope of cotα = 1.5. Secondly, the influence of the packing density showed varying failure mechanism. When applying a large packing density (np = 0.20) the damage occurred below SWL. Contrary to small packing densities (np = 0.35) where damage occurred higher than SWL. It was found that, from the tested packing densities, a packing density of 0.28 gives the best results for both slopes. This conclusion is conform the findings of previous tests [Van Gent et al, 1999]. During these tests an optimum packing density of np = 0.25 – 0.30 was found. Although the cubes were placed randomly in the tests of Van Gent. In this study the cubes were placed in a stretching bond. Finally it was found that a wave steepness of s0p = 0.04-0.05 causes minimum stability for the armour layer. The tests with a single armour layer of cubes placed in a stretching bond indicated that high stability numbers (Hs/ΔDn) can be reached before failure occurs (Nod &gt; 0.2). the tests show that stability numbers as high as 4.5 can be realized before Nod &gt; 0.2 is reached.
DOI: 10.4121/uuid:4c862fa0-fff7-47fd-a824-78fdb28af19b
title: Reduction of wave overtopping by Vetiver grass

description: In this research Vetiver grass is investigated as outer slope protection in order to reduce wave overtopping discharges. In consequence sea dike crest can be reduced. Beside it, this research also focuses on addressing the hydraulic effects of flow and Vetiver hedges. Physical model is conducted full-scale of Vetiver grass and wave parameters in front of the hedge. Mature Vetiver grasses are used for testing and wave is simulated by dam-break method. Experimental results have shown that resistance between flow and Vetiver hedge depends on grass density. In this research, Mannings coefficient is used to describe the resistance; it varies with the changing of flow depth. One interested characteristic of Vetiver grasses showed in this experiment is that its ability to withstand flow of backwater which reaches depths up to nearly 0.4m. The reduction of wave overtopping of more than 60% is measured. The roughness coefficient of Vetiver grass that depends on grass density is found to be varying between 0.33 and 0.41.
DOI: 10.4121/uuid:68f6d174-0770-4d9d-a144-5f9fca0e736d
title: Open filters in breakwaters with a sand core: study into the stability of granular geometrically open, hydraulically sand-open filters in breakwaters with a sand core

description: Physical model tests for this study have been performed in the long sediment transport flume of the Fluid Mechanics Laboratory. This flume is equipped with a wave generator that loads the structure with the desired wave spectrum. The results have been analysed for relations between loading and erosion.
DOI: 10.4121/uuid:963e9fae-e50d-403d-90c7-a273aeb730f7
title: Stability of open filter structures

description: The goal of this research was to verify the formula found by Hoffmans [2012] for structures loaded by currents (flow parallel to the filter construction). As part of the verification of the design formula ten flume experiments were performed in the Environmental Fluid Mechanic Laboratory at Delft University of Technology. After the execution of the model tests an extensive analysis was made based on the performed model tests and model tests performed in the past (Bakker [1960], Haverhoek [1968], Wouters [1982], Konter et al. [1990], Van Huijstee and Verheij [1991] and Van Velzen [2012]).
DOI: 10.4121/uuid:9a84f1aa-01dc-4e1e-bb73-fe93c84f943c
title: Experimenteel onderzoek naar het effect van Ground Consolidators op golven (Anome)

description: De meetresultaten van proeven met GC’s (Ground Consolidators) die zijn uitgevoerd in november en december 2009 in het Laboratorium voor Vloeistofmechanica van de TU Delft. Het doel van de proeven is het verkrijgen van inzicht in de hydraulische eigenschappen van GC’s en de optimale vorm van een GC-kunstrif onder golfbelasting. De proeven zijn uitgevoerd ter voorbereiding op de bouw van een kunstrif bestaande uit GC’s in de Waterproeftuin. Dit is een proefgebied in het Markermeer waar initiatiefnemers de gelegenheid wordt geboden om ervaring op te doen met innovatieve materialen en technieken. De Waterproeftuin is een onderdeel van het Ontwikkelingsplan Markermeer-IJmeer, ter ontwikkeling van een gezond ecologisch systeem en een klimaatbestendig watersysteem in het Markermeer en IJmeer. Er is gekozen voor een aanpak met ‘bouwblokken’, waarbij een rif opgebouwd wordt uit elementen gevuld met GC’s. Op die manier wordt een dataset verkregen voor een aantal elementaire vormen. Een opdrachtgever hoeft dan slechts zijn eisen op te geven en in korte tijd kan een GC constructie ‘ in elkaar gezet’ worden, zonder dat daar nog veel ontwerp tijd in gaat zitten.
DOI: 10.4121/uuid:a66190ca-5a88-4cc2-a4b8-401b21eb77c0
title: Numerical and experimental research of wave interaction with a porous breakwater

description: The design formula for rubble mound breakwaters by Van der Meer has an unclear Notional Permeability term. This term causes a lot of confusion for designers. In the past many people have tried to derive a better formulation for that term by experimental and analytical research. The goal of this study was to obtain a better formulation along a numerical way. This study explores the numerical possibilities and tries to define which direction has to be taken in future research. As a first step, a very simplified case is taken with a vertical homogeneous breakwater which interact with monochromatic waves. In total six different blocks were made of epoxy and elastocoast. Only 4 out of the 6 blocks were tested. Also the porosity (n), laminar friction (α) and turbulent friction constant (β) of the blocks were determined experimentally. This way the experimental results could be compared with computations. These experiments have been done in the large flume of the Environmental Fluid Mechanics Laboratory of the TU Delft. Two types of data were collected: pore pressures and water levels in front and behind the block. The water levels seemed to be the most reliable data. The main deficit of the setup was the wave absorber at the end of the flume. The wave absorber is not able to sufficiently absorb long waves. So the dataset had to be corrected for that effect. The created dataset was in line with results from earlier experiments.
DOI: 10.4121/uuid:abcfafc7-21f7-4f59-9b9e-bcc49708487e
title: Stability of Iceland type berm breakwaters

description: The goals of the project are the following: a) Design rules for the transaction of stone classes with depth have not yet evolved and the main goal of this project was to develop a stability criterion for the stones in that area (Primary goal). b) Stones on berm. Since the total amount of the largest stones (Class I) is usually limited, the combination of the amount of large stones on the berm and down the berm is important (Secondary goal). c) Recession. Recession will be measured in each test and thereby a large database on the subject will be made available for further research on the subject (Secondary goal). d) The location of the transition of the original and the reshaped profiles as the berm height changes as well as for different stone setups. This is also closely related to the primary goal of the project (Secondary goal). Numbers of model tests were performed in order to reach those goals.
DOI: 10.4121/uuid:b54162ae-1b09-450b-a258-535d78040b60
title: Experimental research on dynamic dredge overflow plumes

description: A preliminary study was carried out to investigate both theory and modelling of dynamic plumes in order to define the knowledge gaps present. The possibilities to fill these knowledge gaps were studied which resulted in carrying out experiments on two interesting influences on the dynamic plume: stripping and vortex divergence. Stripping is defined as the removal of material from a dynamic plume by the cross flow. Its process is not well understood and the few quantifications presented in literature were found to have no proper base. To obtain more information laboratory experiments were performed at a 1:100 distorted Richardson scale. The experiments were partly hindered by the limited flume dimensions of the experimental setup, but the tests yielded interesting observations. Vortex divergence is depending on the strength of the vortex pair that is formed when a plume is bent over by a cross flow. In homogenous surroundings the plume is said to be non-bifurcating, but the vortices of the vortex pair are diverging at a near constant rate. This divergence was already observed in the stripping experiments and was further investigated in extra specialized experiments.
DOI: 10.4121/uuid:c1f01480-fa19-4e80-a912-df095e118959
title: Experimental research on the effects of surface screens on a mobile bed

description: The main part of this study is an experimental study on the effects of surface screens on a mobile bed. The design of the physical experiments requires choices about the geometry of the flume. The experiments were carried out with a straight flume and with a dividing wall. Preparing the experiments requires information about the flume facility. The experiments have been carried out in the Environmental Fluid Mechanics Laboratory of DUT. The upstream boundary conditions are discharge and velocity distribution. The downstream boundary condition consisted of a fixed water level. The water level was kept constant along the natural slope of the surface. The experiments consist of taking velocity and bed level. The angle of attack and the penetration depth were chosen to be variable. The angle of attack was varied between 15 and 25 degrees. With these relatively small angles the screen acts as guidance for the flow, instead of an obstruction. The penetration depth was varied between 20% and 60% of the water column. The initial test run determined the optimal measurement duration and the initial equilibrium. Four representative cases have been described in detail, giving support to the general conclusions. The flow pattern changes under influence of the surface screen. The main flow direction is guided by the screen, introducing a transverse velocity at the surface. As flow continuity in the flume has to be maintained, the water near the bottom is forced to have a transverse velocity in opposite direction. Redistribution of the suspended transport and the bottom transport was induced. This generated locations were the actual transport did not meet the transport capacity, which gives rise to morphological changes. Next to the spiral motion the screen had an effect on the longitudinal flow velocities. The attacked side of the flume experiences a higher velocity, thereby having a higher transport capacity. This higher capacity gives rise to local erosion of the bed. At the unattacked side, sedimentation occurs, thereby rising the bed level. In the B-series of the experiment a dividing wall was added. The screen in front of the bifurcation gave rise to the same two processes, but the wall introduced an extra effect. The screen influenced the bifurcation relationship. The bed level adapted to the new conditions. The upstream effect of the bifurcation is explained by changes in water level topography, thereby influencing the backwater curve. In general the wall amplified the morphological development of the bed.
DOI: 10.4121/uuid:c279473a-1a23-4938-934b-01bc2aa5aec5
title: Breakwater stability with damaged single layer armour units

description: The main objective of this research is to determine the effect of single layer armour unit breakage on the hydraulic armour layer stability and potential damage progression. A 2-dimensional model of a rubble mound breakwater with typical cross section was tested with individual and clustered positioned broken Xbloc armour units around the still water line. The residual stability of the armour layer was determined. The armour unit displacement and damage progression was assessed. It is concluded that breakage of single layer armour units has a significant negative effect on start of damage of the armour layer. Breakage of single layer armour units has no significant effect on failure of the armour layer. This damage behaviour leads to a long and gradual damage progression. This type of damage progression looks more like the damage progression of an armour layer consisting of rip-rap rock. The majority of the broken parts show little to no movement. It is therefore unlikely that rapid damage progression occurs due to broken parts damaging other units.
DOI: 10.4121/uuid:cea66f95-c6e5-4173-af01-1c7384417d79
title: Experimental research on spatial distribution of overtopping

description: The scope of this thesis is to find an empirical formula to describe the distribution of overtopping at the space behind the crest. In this research, a physical model was developed on which irregular waves are tested. Because of the duration of the tests and the amount of collected water (significant lose of water during the test), a completely new measuring system was designed. Five influencing parameters (variables) are considered on this research: wave height, wave period/steepness, slope angle, crest freeboard and crest permeability. The entire overtopping process is analysed separately for the total overtopping discharge, the overtopping discharge directly behind the crest and the distribution of overtopping behind the structure. In the analysis of the data collected from the measurements, the impact of the varying parameters is investigated leading to useful conclusions and better understanding of the entire process. Additionally, the experimental findings are analysed and compared to the relative existing methods.
DOI: 10.4121/uuid:d9d1483a-8508-4443-aa93-0d7a5c503776
title: Wave overtopping at rubble mound breakwaters with a non-reshaping berm

description: Wave overtopping was investigated by means of a physical model. The breakwater scale model was divided into 8 collection bins. Overtopped volumes were collected and pumped into floating tanks further down the flume. After the experiment the mass of the floating tanks was measured and the mean overtopping discharge could be determined for 8 horizontal positions on the breakwater. The measured total overtopping discharges cannot be predicted accurately by existing prediction methods. On the basis of experimental data a new prediction method was proposed that achieves an excellent fit for total overtopping. The crest freeboard definition was adjusted to account for the permeability of the crest. The reduction factor accounting for slope roughness was made dependent on the Iribarren number. For Iribarren numbers higher than 6, this method calculates no reduction of overtopping due to slope roughness. The effect of a permeable berm on total overtopping was found to be remarkably different from the effect of an impermeable berm. Permeable berms below Still Water Level (SWL) lead to less reduction of overtopping than impermeable berms below SWL. Berms above SWL lead to wave breaking on the slope in front of the berm. Contrarily to impermeable berms above SWL, a permeable berm above SWL leads to significant reduction of overtopping. The measured spatial distribution of overtopping is associated with a lot of seemingly random behaviour. Large differences were found with the experimental data of Lioutas (2010). It is suspected that the used experiment setup gives rise to significant model effects for the spatial distribution of overtopping. An experiment setup was recommended that is expected to more accurately model the behaviour of the prototype situation. Data on the spatial distribution of overtopping could not accurately be predicted by existing prediction methods. In some cases existing prediction methods provided an upper limit for overtopping (Juul Jensen, 1984) but none led to a good fit with the experimental data. A new reduction factor was found that reduces the amount of scatter and provides a conservative prediction of the experimental data.
DOI: 10.4121/uuid:e39a669a-75e5-4040-b715-fa40aec57bfa
title: The influence of core permeability on the stability of interlocking, single layer armour units

description: The permeability of a breakwater is of great importance for the stability of the armour layer. The influence of the structural permeability on the stability of rock armour units was already researched by Van der Meer using the 'notional' permeabiltiy. However, for single layer interlocking armour units the influence core permeability is rather unfamiliar. The goal of this research is to extend the knowledge on the failure mechanism of the armour layer for different structural permeability. To achieve this goal, model tests are conducted in the permeameter of the Technical University of Delft and in the wave flume of Delta Marine Consultants, Utrecht. The tests show that the stability of the armour layer decreases with increasing and decreasing core permeability.
DOI: 10.4121/uuid:e486174c-32e2-466a-a850-f97d80c82fc7
title: Extraction Force Xbloc: Model Tests

description: This study describes the influence of the slope angle of a breakwater slope, the density of the concrete of the Xbloc armour unit, the vertical position of the Xbloc on the breakwater slope and the roughness of the under layer of the breakwater on the extraction force of an Xbloc armour unit. By testing the extraction force, indirectly the influence of all parameters above on the Xbloc unit interlocking capacity can be described. This research has been done by doing model tests with small scale Xbloc units.
DOI: 10.4121/uuid:6cb98f84-f0de-47d4-8a2c-d6aaeaf5db08
title: Limpopo National Park (Mozambique) Soil Organic Carbon study

description: 410 field observations of topsoils in Limpopo National Park (Mozambique), 128 of which were analyzed by wet chemistry for ph, soil organic C, sand, silt, clay; all of which have predicted soil organic C concentration by lab. spectroscopy calibrated with lab. analysis
DOI: 10.4121/uuid:175deb68-3450-4200-a6fc-ad25c17513d6
title: Physical model tests of the notional permeability on breakwaters

description: In the water laboratory three models were tested. Firstly, model 3 of Kik is repeated as model 3A, with a calculated value of notional permeability P 0.38. The construction of model 3A is build with a top layer, filter layer 1, filter layer 2 and a impermeable core. Second, another variant of model 3 of Kik is designed and tested (model 4). However, the measured damage figures were too low and therefore they could not be used to calculate a value for the notional permeability P. The construction of model four is build with a top layer, filter layer 1, filter layer 2 which is thicker as model 3A and an impermeable core. Finally, model 5 is tested with a calculated value of notional permeability of P 0.45. This model is designed from the fourth construction of Van der Meer. The construction of model 5 is build with a top layer, filter layer 1 and a permeable core with the same material of filter layer 2 of model 3A and model 4. The results of this research show that the influences of the notional permeability P exists of the ratio of the armour layer thickness and the thickness of the second filter layer. If the layer thicknesses are equal the value for notional permeability P is 0.38, which follows from model 3A. If the second layer has an infinite thickness (permeable core), the value for notional permeability P is 0.45, which follows from model 5. The value of the notional permeability P of model 5 corresponds to the design calculations of the computer model HADEER. Van der Meer discovered using this computer model that the ratio of dn50a/ dn50f = 5 has a value on the notional permeability P of 0.43 –0.44. During this research, while using two different methods, a value of the notional permeability P of 0.45 was calculated.
DOI: 10.4121/uuid:52ea146f-2754-4231-a20b-c073fae181b9
title: Turbulence in shallow jet flows

description: The general flow pattern of an open channel flow, downstream of a width restriction by two artificial dams, is analysed. A physical Froude-scaled model, under hydraulic rough conditions, with a significant large Reynolds number is used to ensure turbulent flow.
DOI: 10.4121/uuid:9db50a98-21e0-4e2e-8179-62ea91c897f2
title: Regeneration of zeolites used for ammonium removal from anaerobic groundwater

description: This research focuses on the chemical regeneration of zeolites which have been used to remove ammonium from anaerobic groundwater. The main goals hereby have been: - The determination of the effect of multiple regeneration on the ion -exchange capacity of the zeolites - The testing of the effectiveness of two types of regenerant: NaOH and NaCl - To see whether it is possible to reduce the amount of chemicals used for regeneration by reusing the regenerant.