Falling aprons at circular piers under currents

Traditional guidelines on rock protection at circular piers predominantly focus on preventing shear failure (by choosing a sufficiently large rock size), winnowing failure (by designing an appropriate filter) and edge failure (by selecting a sufficient extent). In particular areas (e.g. in an eroding river channel or in an area with large-scale...

Jet scour

This paper discusses scour without bed protection, such as propeller scour, two-dimensional horizontal, three-dimensional horizontal scour generated by free jets downstream of gates and outlets, two-dimensional vertical and three-dimensional vertical scour. The flow velocities in two- and three-dimensional propeller and free jets are briefly...

Comparison of water jets and conventional propeller jets

Conventional ship propulsion systems and hydro jets differ in many ways. However, they are both responsible for sailing and manoeuvring of ships in a forward or reverse direction. The hydrodynamic jet is what they have in common, but the characteristics of the jets differ. For example, the outflow velocity of hydro jets is much higher than the...

Kribben en ijsdammen

Shear stress concept in granular filters

Scour is a natural phenomenon caused by the flow of water in rivers and streams and occurs as a part of the morphological changes caused by rivers or as a result of man-made structures. For the Dutch Delta Works hydraulic structures were often constructed on fines with loose packing. To guarantee the geotechnical stability of these structures...