Making water flow: a comparison of the hydrodynamic characteristics of 12 different benthic biological flumes

Abstract

Flume tanks are becoming increasingly important research tools in aquatic ecology, to link biological to hydrodynamical processes.There is no such thing as a ''standard flume tank'', and no flume tank is suitable for every type of research question. A series of experiments has been carried out to characterise and compare the hydrodynamic characteristics of 12 different flume tanks that are designed specifically for biological research. These facilities are part of the EU network BioFlow. The flumes could be divided into four basic design types: straight, racetrack, annular and field flumes. In each facility, two vertical velocity profiles were 2006 measured: one at 0.05 m s -1 and one at 0.25 m s -1 . In those flumes equipped with Acoustic Doppler Velocimeters (ADV), time series were also recorded for each velocity at two heights above the bottom: 0.05 m and 20% of the water depth. From these measurements turbulence characteristics, such as TKE and Reynolds stress, were derived, and autocorrelation spectra of the horizontal along-stream velocity component were plotted. The flume measurements were compared to two sets of velocity profiles measured in the field.Despite the fact that some flumes were relatively small, turbulence was fully developed in all channels. Straight and racetrack flumes generally produced boundary layers with a clearly definable logarithmic layer, similar to measurements in the field taken under steady flow conditions. The two annular flumes produced relatively thin boundary layers, presumably due to secondary flows developing in the curved channels. The profiles in the field flumes also differed considerably from the expected log profile. This may either have been due the construction of the flume, or due to unsteady conditions during measurement. Constraints imposed by the different flume designs on the suitability for different types of boundary layer research, as well as scaling issues are discussed.

Erosion threshold of saturated natural cohesive sediments: Modeling and experiments

“…It is a straight recirculating facility, which was designed and built [Dumas, 2004] to study the erosion of sediments and provide a wider bed shear stress range than in the flume already used at the Centre d'Océanologie de Marseille (see for details Jonsson et al [2006]). The overall length of the channel is 13.5 m. Its test section is 8 m long, with a rectangular cross section of 0.6 m width.…”

Remobilization of heavy metals during the resuspension of Liangshui River sediments using an annular flume

“…One is the particle entrainment simulator (PES) designed by Tsai and Lick [4]; the other is flume tank [5]. Among flume tanks, annular flume has been extensively used to investigate various physical, chemical and biological factors which may influence the stability and erodibility of natural cohesive sediments [6][7][8][9][10].…”

Experimentation at the interface of fluvial geomorphology, stream ecology and hydraulic engineering and the development of an effective, interdisciplinary river science

“…Nowell and Jumars (1987) recommended that flumes for use in biological experiments should have a width to depth ratio of at least 5 to 1 in order to reproduce realistic boundary layers. In a recent review, Jonsson et al (2006) concluded that the ratio between the width of the flume and the wall boundary layer thickness (δ) is a more important consideration, recommending that flume width should exceed 2δ + k where k is a relevant length scale of the organism under investigation. Similarly, an ecologist aware of the diel activity and light sensitivity of aquatic insects may question the value of examining the movements of negatively phototactic species on flume beds that are brightly lit or lacking shelter (Barmuta et al, 2001).…”

“…Jonsson et al, (2006) recently made a direct comparison of a selection of facilities with the aim of identifying those flumes best suited to the study of benthos-flow interactions in marine environments. In general, however, we are unaware of attempts to define facility protocols or best-practice procedures.…”