Stability of coarse granular structures: Investigation on micro-scale

Entraining Flow of a Concentrated Benthic Suspension: Computations with the Prandtl Mixing-Length Model

The Prandtl mixing-length model of turbulent exchange of mass and momentum is applied to calculate the entrainment of overlying water into a layer of suspended fine sediment at a horizontal bed. In the field the flow and turbulence in such a concentrated benthic suspension (CBS) are driven by a streamwise pressure gradient resulting from the...

A pilot study to test a method to enhance the turbulence of a water flow in a laboratory flume

In this report we present some results of a laboratory pilot study which has been conducted to test a method to artificially enhance the turbulence of a water flow in a laboratory flume. The purpose of this test is to provide data which will be used to verify whether the method is suitable for the study of the dissipative effects of turbulence...

Recirculating steady flow in harbours: Comparison of numerical computations to laboratory measurements

In this report the water flow in harbours, that are situated on a river, are considered. Due to the flow velocity difference between the river and the harbour, a turbulent mixing layer develops at the harbour entrance. The shallowness of the water induces the coexistance of two disparate turbulent length scales in these regions. Besides the ...

Flow measurements for an afterbody in a vertical wind tunnel

Influence of turbulence on the derivation of the drag from wake measurements

Dynamic forces on a bed element in open channel flow with a backward facing step

Experiments to measure forces on objects in open channel flow behind a bacward facing step

Local Scour: Damping of turbulence parameters in relaxation zone

The general purpose of this research project is to model mathematically the scour-hole downstream of a structure (2-D). The model has to simulate the development of the scour as a function of time. Basically two models are necessary namely a flow model and a morphological model. The latter has to describe the bed- and suspended load and the...

A k-Model for Stably Stratified Nearly Horizontal Turbulent Flows

A k-model is formulated that consists of the turbulent kinetic energy equation and an algebraic expression for the mixing length taking into account the influence of stratification. Applicability of the model is restricted to shallow, nearly horizontal flows. For local-equilibrium flows the model reduces to the well-known mixing-length...

Reproduction of Velocity Profiles in Estuaries by some One-Dimensional Mathematical Models

For the prediction of dispersion phenomena and of changes in the morphology of an alluvial bottom, a detailed description of the water flow is necessary. The flow in estuaries is a complicated one, partly because of the time-dependence. To isolate this aspect of tidal flow a simplifying one-dimensional (vertical) flow model 1S used. This one...

Experiments on Unsteady Seperating Flow in an Open Channel

Experiments on unsteady separating flow past a sudden expansion in an open channel are described. To simulate tidal flow the flow rate in the approach channel varied as a half-sine with time. Different visualization techniques to obtain an insight into the behaviour of the separating vortex in time and space were used. Laser-Doppler velocimetry ...

Steady turbulent flow in curved rectangular channels

After the study of fully developed and developing steady laminar flow in curved channels of shallow rectangular wet cross-section (see earlier reports in this series), steady turbulent flow in such channels is investigated as a next step towards a mathematical model of the flow in shallow river bends. A mathematical model is developed for this...

Gedaechtniseffekte in der Turbulenz

NOTE: REPORT IN GERMAN, ONLY THE ABSTRACT IS IN ENGLISH Memory effects in the flow of fluids are known long since. One has to reckon with such effects when studying the flow of non-Newtonian fluids, for instance when they exhibit a visco-elastic behaviour. Certain phenomena in turbulence also seem to point towards a visco-elastic behaviour. If,...

A model of turbulent diffusion

Mathematical description of turbulent diffusion with constant mean velocity gradient.