 |
| Titel |
Entrainment by vortices |
| VerfasserIn |
J. M. Redondo, P. Medina, X. du Madron, P. Furmanek |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250030957
|
|
|
|
|
|
| Zusammenfassung |
| Grid stirred turbulence in a zero-mean-flow environment is used to lift-off a sediment
bed of different size particles, variations of the r.m.s. turbulent velocity, the integral
length scale of the turbulence and the local vorticity may be varied according to the
distance between the grid and the sediment bed. The geometrical characteristics of the
entrainment process as well as the scouring patterns are related to the local Richardson
number defined in terms of the sediment induced buoyancy. These characteristics may
be used in paleo-sedimentology relating geometrical to dynamical aspects of the
turbulent forcing.
The quantification of lift-off from zero-mean and shear generated turbulence is
compared taking into account the structure of the turbulence as it approaches a sediment
laden bed. The cohesive characteristics of the type of sediment as well as its size are
important. It is very important to estimate the PDFs and the intermittency associated to
the type of flow that entrains the sediments, because in many cases, only the most
energetic events are relevant to the sediment transport. |
|
|
|
|
|
|