2026 CSDMS meeting-018
From CSDMS
(if you haven't already)
Log in (or create account for non-CSDMS members)
Forgot username? Search or email:CSDMSweb@colorado.edu
Browse abstracts
Measurement of turbulent pressure fluctuations to inform plucking and entrainment thresholds
Nicholas Colaianne,
(he/him),University of Idaho Center for Ecohydraulics Research Boise Idaho, United States. cola8842@vandals.uidaho.edu
The detachment of intact blocks of substrate material from channel surfaces by flow hydraulics (“plucking”) is a key mechanism driving erosion in both natural and man-made channels. Despite its role in knickpoint migration and channel boundary adjustment, the physical processes controlling block motion remain poorly constrained. In particular, we lack measurements of the instantaneous turbulent pressure field and its interaction with block geometry and fracture networks at the onset of motion. Turbulent fluctuations contribute to the forces acting on objects exposed to flows and may act to initiate motion even when bulk flow metrics remain steady. This project directly measures turbulent pressure fluctuations acting on a simulated bedrock block at a downstream-facing step in subcritical, critical, and supercritical flows to quantify the forces contributing to fluvial plucking. Laboratory flume experiments employ a “bedrock” cube instrumented with 66 pressure transducers and two accelerometers, enabling simultaneous measurement of instantaneous pressures and block motion. Block protrusion (−20 to +20 mm) and fracture (joint) width (0–100 mm) are systematically varied to quantify their effects on the lift and drag forces and the sequence of block motion, including initial lift, rotation, and translation. I use planar particle image velocimetry (PIV) to resolve the near-bed velocity field and shear stress acting on the block top. The resulting dataset will provide new mechanistic insights into how flow turbulence and fracture geometry control block entrainment which may be applied to existing erosional frameworks and models of bedrock plucking such as the Hurst 1D erosion (H1DE) model.
