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Shallow Turbulent Flows

 

Shallow Flows in our environment

Shallow flows exist where the horizontal length scales of the flow domain are much larger than the depth.  Such shallow flows are ubiquitous in nature, ranging from river, estuarine, and oceanic flows to stratified flows in the atmosphere.  Although turbulent eddy size is typically limited by the shortest dimension, large-scale coherent turbulent structures are observed in shallow flows with length-scales orders of magnitude greater than the depth.  Shallow flows is also the subject of an IAHR conference series: the first Shallow Flows conference was held in Delft, The Netherlands in 2003 and the second one will be held in 2008 in Hong Kong, China. As an example see to the right a picture of Argo Merchant, an oil tanker (200 m long) that run aground in December 1976 in 3m shallow waters near Natucket Island generating a vortex street of the order of hundreds of meters.
See some examples of oceanic and atmosperic wakes, plumes and vortices in our environment: Jan Mayen Island, Guadalupe Island, Madeira Island, Queen Charlotte Island, Tasman Sea, ashplume of Mt. Etna, Italy.

Vortex street behind Argo Merchant in 3m shallow waters (visualised by crude oil).

Satellite pictures of atmospheric and ocean wakes, plumes and vortices [NASA].


visualization of cylinder wakes in the shallow water basin (IfH).

Laboratory Experiments and Numerical Studies

Our research at IfH includes experimental, analytical and numerical work.  The laboratory experiments include Laser Doppler Velocimetry (LDV) measures of the turbulent flow characteristics coupled with Laser Induced Fluorescence (LIF) to understand the short time- and space-scale turbulent transport characteristics of the flow.  Laboratory experiments also include Particle Image Velocimetry (PIV) coupled with Planar Concentration Measurements (PCA) to study the basin-scale transport characteristics of the large coherent structures.  These laboratory data are then used to interpret numerical stability analysis  focused on the stability of these shallow wakes. The different stability regimes determine the fashion in which these large-scale structures detach from the obstacle; thus, they determine the nature of the turbulent transport.

 

Further Sites

State-of-the-art non-intrusive measurement techniques were adapted and developed for appropriate use in the IfH - Shallow Water Basin. Among them are Particle Image Velocimetry - PIV, Particle Tracking Velocimetry - PTV, Laser Doppler Velocimetry - LDV-LIF, Planar Concentration Analysis - PCA.

A list of projects related to the IfH - Shallow Water Basin can be found here:

Publications related to projects carried out in the IfH - Shallow Water Basin can be found in the references list.

Mass concentration in LCS in shallow cylinder wake flow [v.Carmer 2005].


Enhanced turbulent mixing in shallow flows by LCS [Rummel et al 2005].


16.11.2007  

rummel (at) ifh uka de