Verification of the pier scour development in the experimental environment

Experiments conducted in the hydraulic flume provide a controlled flow environment, which often provides means for prompt qualitative investigation of general flow structure. Under the R3PEAT project (www.grad.hr/r3peat), research focus is on the scour at bridge piers protected by the riprap sloping structure – investigated using both physical and 3D numerical model. Experimental data, while constrained by the flume dimensions and the pump capacity, measured with high frequency Vectrino Profiler’s provide detailed insight into turbulence around the structure. Experimental models are set-up as segments of the river extruded from the bathymetric and hydraulic surveys, corresponding to the flume size and selected scaling. Based on the experimental data, 3D numerical model will be calibrated in order to investigate flow conditions for the relevant floods with design return period, exceeding the flume capacity. Physical model therefore must reliably present the prototype bridge, through resulting flow field in the pier vicinity. This paper presents verification of the physical model using field ADCP measurements. ADCP velocities are compared to experimental data on the 4 cross-sections adjacent to the bridge, adapted to the relative flume streamwise orientation. Advantages and disadvantages of the physical model usage as benchmark for numerical model setup are discussed.

Acknowledgments
This work has been supported in part by Croatian Science Foundation under the project R3PEAT (UIP-2019-04-4046).