ISSN:
1420-9055
Keywords:
Key words: Lutocline, fluidized bed, suspended sediments, vertical jet.
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract: An experimental study was carried out to investigate the resuspension of particles by a momentum jet discharging from below into a conical basin. The work was motivated by its relevance to Lake Banyoles, where sediments are suspended in different conical basins by bottom jets fed by a groundwater karstic system. Two different flow regimes were identified: a "Jet Flow" regime (JF) and a "Lutocline Flow" regime (LF). In the LF regime, the particles were resuspended, forming a well-established interface along the entire cross-sectional ara of the cone. This regime occurs when the particle Reynolds number $ {\bf Re_p = (u-w_s)d_p/ \nu} $ where u is the mean velocity of the flow at the jet entry, w s is the settling velocity of particles, d p is the diameter of that particles and $ {\bf \nu} $ is the kinematic viscosity of water) is below a critical number Re c that depends on the slope of the basin. The maximum height to which particles rise in the LF regime was also determined as a function of four non-dimensional variables: D 1 = h o /(M o 1/2 /w s ), D 2 = h o /d p , Re p and $ {\bf tan \, \beta} $ (where h o is the height of the particle bed, M o is the kinematic momentum flux of the jet and $ {\bf tan \, \beta} $ is the slope of the basin). Application of the results to the basins of Lake Banyoles showed a good agreement provided that the aggregate properties of the suspensions are used. It is also shown that, in the LF regime, inflows to the basins can be estimated by a simple technique based on a balance between the sedimentation flux and the upward advection of sediments by the mean flow.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s000270050077
