Obstacle-Reynolds-number based analysis of local scour at submerged cylinders

Abstract

A simple process-based, analytical approach is developed and validated herein to determine the local scour at obstacles in the fluvial environment. It is based on the obstacle Reynolds and Froude numbers. Clear-water flume experiments were conducted to investigate the local scour depths at submerged cylinders in coarse uniform sand. The resulting scour depths were correlated with an analytical model and validated with two data sets on local scour at submerged and emergent cylinders. The size of the projected frontal obstacle area in relation to the mean flow velocity has a significant effect on the scour hole shape and depth. A power law function is derived that satisfactorily describes the present scour depth data. The approach is limited to nearequilibrium clear-water scour, uniform sediment and excludes particle density effects.

Influence of inclination and permeability of solitary woody riparian plants on local hydraulic and sedimentary processes

“…For the analytical determination of the deposited sediment volume, a previously developed model (Euler and Herget, ) can be applied. Thereby, the projected frontal area is expressed as a length value (L A ), with L A = h o 2/3 w o 1/3 , where h o = obstacle height and w o = obstacle width.…”

“…For the analytical determination of the deposited sediment volume, a previously developed model (Euler and Herget, 2011) (Fr) is incorporated so that the following functional relationship is given:…”

Fluvial islands: First stage of development from nonmigrating (forced) bars and woody-vegetation interactions

“…Digital elevation models (Fig. 6) show a relatively plane surface of the bar in 2007 with superimposed low-amplitude longitudinal obstacle marks (Nakayama et al, 2002;Rodrigues et al, 2007;Euler and Herget, 2011;Euler et al, 2014) caused by the presence of patches of young trees.…”

Comparisons of Local Scouring for Submerged Square and Circular Cross-Section Piles in Steady Currents

“…Owing to the high flow intensity of the Shields number, the distributions of scouring and deposition for the two pile shapes did not show clear differences. Euler and Herget [18] stated that the size of the submerged piles and the approach flow velocity have significant effects on the scour hole shape and depth.Motivated by (i) the necessity of further research into the local scouring of submerged vertical piles, (ii) the significant effect of the flow intensity and pile height on local scouring, and (iii) a lack of comparisons between CC and SC piles, in this study, three experiments were conducted to determine the local scouring of two representative SC piles and one CC pile. Emphasis was given to the evolutions of the key points of the scour depths, bed profile elevations, scour and deposition distributions, and streamlines around the piles.…”

“…Owing to the high flow intensity of the Shields number, the distributions of scouring and deposition for the two pile shapes did not show clear differences. Euler and Herget [18] stated that the size of the submerged piles and the approach flow velocity have significant effects on the scour hole shape and depth.…”