Submitted to: International Conference on Scour of Foundations
Publication Type: Proceedings
Publication Acceptance Date: 4/30/2002
Publication Date: 5/30/2002
Citation: KUHNLE, R.A., JIA, Y., ALONSO, C.V. 3-DIMENSIONAL MEASURED AND SIMULATED FLOW FOR SCOUR NEAR SPUR DIKES. First International Conference on Scour of Foundations, ICSF-1, Texas A&M University, College Station, TX. 21002. p. 349-363. Interpretive Summary: Streams in agricultural watersheds are often plagued with unstable channel boundaries. Erosion of the unstable channel boundaries threatens valuable agricultural and other lands. Excess sediment from erosion also degrades the habitat for fish and other aquatic organisms. Bank protection measures have the potential to preserve valuable agricultural lands and enhance aquatic habitats. A study was conducted in the laboratory using a model stream channel to accurately measure the 3-D flow velocities in the vicinity of a model spur dike (a structure widely used to protect stream banks). The flow in the vicinity of spur dikes is very complicated and poorly known. The measured flow velocities were compared with the calculated velocities from a computer model (CCHE3D). The comparison between measured and calculated flow velocities was excellent. This study represents an important step in the improvement of the design of effective structures for channel erosion control and enhancement of the aquatic habitat. Improved tools for structure design and analysis are needed by managers concerned with agricultural watersheds.
Technical Abstract: To improve understanding of the flow and scour processes associated with spur dikes more fully, 3-dimensional flow velocities were measured using an acoustic Doppler velocimeter at a closely spaced grid over a fixed flat bed with a submerged spur dike. Some 2592 three-dimensional velocities around a trapezoidal shaped submerged spur dike were measured. General velocity distribution and detailed near field flow structures were revealed by the measurement. Some important differences between the flow fields measured in this study and those measured for non-submerged vertical obstructions were observed in this study. Numerical simulation was performed using the free surface turbulent flow model, CCHE3D. The numerical simulation of the flow showed very good agreement between the computation results and the measurements. The numerical simulation results indicate the CCHE3D model can be used to predict near-field flows around hydraulic structures.