DBPapers
DOI: 10.5593/SGEM2014/B31/S12.047

HYDRAULIC FRICTION COEFFICIENT OF STREAMS DUE TO SEDIMENT TRANSPORT

A. VIRSTA,N. PETRESCU,M. A. SANDU, P. MOCANU, D. IORDAN
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-13-1 / ISSN 1314-2704, June 19-25, 2014, Book 3, Vol. 1, 361-366 pp

ABSTRACT
The paper presents the influence of riverbed morphology on the flowing resistance and water head losses. The mechanical work of friction forces in the river bed shows that the dunes correspond to the minimum value of dissipated energy. The foreign and Romanian researches, assume higher values of flowing resistance in the conditions of existing dunes than in the conditions of flat riverbeds. The results were obtained by laboratory modeling. The experiments were conducted into a 600 cm long, 30 cm wide and 20 cm deep rectangular flume. The upstream section consists of a reception area for sediments. A fixed bed to ensure the turbulent boundary layer was fully developed before reaching the test section. The test reach was composed of a movable bed with fine sediment to a depth of 10 cm. The downstream section consists also in a fixed bed and has a sand trap. The sidewalls of the flume were made of glass, while the flume itself was constructed on pillars. The airflow on the model is due by a fan working in aspiration stream. The experiments have shown that, at low depth of stream, the dunes determine lower hydraulics resistances. These results could be explained by reshaping of riverbed, head loss having minimum values. These results have to be validated by a new series of experiences, and the paper suggests the future research directions.

Keywords: Friction Coefficient, Flume, Laboratory modeling