Experimentally obtained velocity and pressure fields of an open channel flow around a cylinder using RIM-SPIV *

The quantification of velocity and pressure fields over streambeds is important for predicting sediment mobility and water exchange between stream and sediment interstitial spaces. The latter is typically referred as hyporheic flow, which consists of surface water that flows through the streambed sediment pores. In this paper, we report an experimental investigation of the time-averaged velocity and pressure field, quantified in a set of laboratory experiments using stereo Particle Image Velocimetry with a refractive index-matched fluid, for an open channel flow around a submerged vertical cylinder as a model for plant stalk over a plane bed of coarse granular sediment.  Full velocity and pressure fields were generated up to and around the cylinder and directly adjacent to the steam bed. The pressure field was calculated from the velocity field using an Omni-Directional, Rotating Ray integration methodology to solve the Reynolds-averaged Navier-Stokes equations. This is the first time that such a velocity and pressure field is characterized experimentally for a free surface flow with irregular floor contour.