Biogeosciences
www.biogeosciences.net
1726-4170
1726-4189
4
3
2007
10.5194/bg-4-269-2007
http://www.biogeosciences.net/4/269/2007/
http://www.biogeosciences.net/4/269/2007/bg-4-269-2007.html
http://www.biogeosciences.net/4/269/2007/bg-4-269-2007.pdf
269
282
2007-05-16
Structure of mass and momentum fields over a model aggregation of benthic filter feeders
J. P. Crimaldi
crimaldi@colorado.edu
J. R. Koseff
S. G. Monismith
Department of Civil and Environmental Engineering, University of Colorado, Boulder, CO, 80309-0428, USA
Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, 94305-4020, USA
The structure of momentum and concentration boundary layers developing over a
bed of <i>Potamocorbula amurensis</i> clam mimics was studied. Laser Doppler
velocimetry (LDV) and laser-induced fluorescence (LIF) probes were used to
quantify velocity and concentration profiles in a laboratory flume containing
3969 model clams. Model clams incorporated passive roughness, active siphon
pumping, and the ability to filter a phytoplankton surrogate from the flow.
Measurements were made for two crossflow velocities, four clam pumping rates,
and two siphon heights. Simultaneous use of LDV and LIF probes permited direct
calculation of scalar flux of phytoplankton to the bed. Results show that
clam pumping rates have a pronounced effect on a wide range of turbulent
quantities in the boundary layer. In particular, the vertical turbulent flux
of scalar mass to the bed was approximately proportional to the rate of clam
pumping.
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