The LABEREX chamber for studying the critical shear stress for fine-grained sediment

Abstract

Geografisk Tidsskrift, Danish Journal of Geography 99: 1–7, 1999

A new portable instrument, the Laberex chamber—LAB oratory ERosional EXperiments—for studies of the “fluff layer” and sediment critical shear stress is described. The chamber consists of a cylindric plexiglass tube with an inner diameter of 84 mm. A four-bladed impeller connected to a motor is placed in the centre of the chamber. Rotation of the impeller induces resuspension. Light attenuation is measured across the centre line in the chamber at a wave length of 633 nm (red light). A PC automatically controls both the stirring voltage that is increased at predetermined time-intervals and collects data from the light attenuation meter every second. Velocity distributions in the chamber and the relation between stirring voltages and critical shear stress are known from laser doppler measurements in the chamber.

Keywords:

• Chamber hydrodynamics
• shear stress
• resuspension
• sediment
• fluff layer