Stability of block mats under flow conditions

Block mattresses or block mats are, nowadays, very commonly applied as protection in a large range of applications either against flow or wave loads. Specifically, this large range of applications contains offshore pipeline protection and stabilization, erosion and scour protection, protection of embankments and river banks (slope protection)....

Effectiveness of a multipurpose artificial underwater structure as a coral reef canopy: Hydrodynamic and ecological connectivity

The following research focuses on artificial underwater structures (a.k.a. artificial reefs) in a coral reef environment to mitigate the natural and anthropogenic pressures which reef systems are increasingly facing worldwide. The research question is stated as: “Establishing a method to determine if a multipurpose artificial underwater...

Incorporation of the effects of accelerating flow in the design of granular bed protections

For the design of granular bed protections often a stability parameter is used. The stability parameter represents the forces that are acting on the stones and is used to predict the response of the bed to these forces. Existing parameters are often derived for a limited range of application. When the parameter is used outside this range, the...

Turbulence in the wake of a roughness patch

Little research was done in the past concerning the propagation of three dimensional effect in shallow wake flow caused by a roughness patch. Today’s research on related subjects is dominated by emerging obstructions in shallow water where the flow can be assumed as (quasi) two dimensional. However the relevance of a submerged obstruction with...

Sharp bend flow: Comparison of Delft3D-FLOW with LES and measurements for sharp bends

For a proper management of rivers and river bends in particular, it is important to have good models to predict the flows through bends. It is important that those developed models are well validated with measurements to demonstrate the usefulness of the models. This research is a validation of the Delft3D-FLOW model which is a model that is...

Cobble Sea Defence: Hydraulic Interface Stability of Sand underlying a Single Filter Layer

A cobble sea defence appears to be an easy constructible protection, with relatively low total costs of ownership. Flume tests show that sand under such single layered constructions is stable. However, it is not exactly known how the hydraulic loading of a breaking wave is reducing in the filter. Two datasets containing pressure measurements in...

Grootschalige horizontale structuren in een rivier met uiterwaarden: Een experimentele studie

Dit afstudeerwerk bestaat uit het ontwerpen van een fysisch model, het uitvoeren van experimenten, het verwerken van de metingen en het interpreteren van de resultaten. Allereerst wordt in hoofdstuk 2 aan de hand van een probleemanalyse ingegaan op de literatuur betreffende de (ondiepe) menglaagstroming en wordt de doelstelling van het...

Eendimensionale beschouwing van de bezinking van hooggeconcentreerde zandwatermengsels onder turbulente omstandigheden

De concentratie van het opgezogen zandwatermengsel en de mate van turbulentie in het beun van een sleephopperzuiger zijn van grote invloed op de snelheid van bezinken van het zandwatermengsel in het beun. Om de kennis van deze invloedsfactoren op de snelheid van bezinken te vergroten is een proefopstelling gebouwd waarin de bezinking van...

Hoofdstroming contra menglaag: De invloed van een menglaag op het begin van bewegen van bodemmateriaal

Experimental research on the stability of bed material behind a backward facing step. Measured is the stability as a function of the local velocity and the local turbulence (turbulence intensity) due to the eddy formation.

Research on a shallow water mixing layer: Derivation of one-dimensional mixing layer model and spatial correlation measurements

A shallow water mixing layer is a flow pattern which develops between two adjacent streams with a different velocity. The horizontal dimensions of a shallow water mixing layer are much larger than the depth. This results in a turbulent process in the mixing layer which is characterized by the presumable presence of two distinct turbulent length...