Author(s): B. A. Johnson; E. A. Cowen

Linked Author(s): Edwin Cowen

Keywords: No Keywords

Abstract: Particle resuspension due to turbulence in a facility designed to achieve low secondary mean flow is investigated to determine an appropriate parameterization of the turbulent stress to define a non-dimensional Shields-like parameter that defines the particle motion regime. Prior laboratory studies have utilized grid-stirred tanks (GSTs) to generate turbulence with little mean shear, however, relatively high levels of mean flow still exist (based, for example, on the ratio of the turbulent kinetic energy to the mean flow kinetic energy). We utilize the recently developed Randomly Actuated Synthetic Jet Array (RASJA), which is more controllable and generates significantly less mean flow relative to GSTs. We filled the bottom of our facility with a layer of sand, which is narrowly graded with a median grain size diameter (D50) of about 250 μm. A particle image diameter based threshold is used to decompose digital images of the flow into fine tracer particle images and the more coarse sediment particle images. Particle image velocimetry (PIV) and particle tracking velocimetry (PTV) are used to observe fluid and sediment velocity, respectively, to study the turbulent structures responsible for sediment resuspension and to determine statistical metrics of the flow. We will discuss our results in the context of traditional boundary layer and critical shear stress findings for sediment resuspension.

DOI:

Year: 2009