Impact of roughness changes on contaminant transport in sewers

Year, pages: 2020, 145 - 151

The paper deals with question how the bed sediment or deposits impact transport processes in conditions of flow with low velocity and water depth. This is often a problem especially in case of flow in sewer network. For this reason, there were performed several tests in laboratory flume having the shape of a pipe with circular cross-section. To simulate the hydraulic condition in sewer pipe with sediments and deposits, some sand was inserted in the pipe with various layer thickness and granularity. It was used a sand of fraction 0.6–1.2 mm. In total, 4 sets of experiments with different layer thickness were performed: with layer thickness of 0 mm (no sediments), 8.5 mm (3.4% of the pipe diameter), 25 mm (10%) and 35 mm (14%) of sand sediment. For each thickness of the sediment layer a set of tracer experiment was performed with different discharges ranging approximately (0.14–2.5) l s-1. Results of the tracer experiments show, that the value of the longitudinal dispersion coefficient Dx in the hydraulic conditions of circular sewer pipe with sediment and deposits decreases when the Reynolds number is decreasing too. The value of Dx reaches its minimal value in the range of the Reynolds number between 4500 up to 10 000. With Reynolds number below this range the value of Dx start to rise.

Sokáč, M., Velísková, Y. 2020. Impact of roughness changes on contaminant transport in sewers. In Acta Hydrologica Slovaca, vol. 21, no.2, pp. 145-151. 2644-4690. DOI: https://doi.org/10.31577/ahs-2020-0021.02.0018

Sokáč, M., Velísková, Y. (2020). Impact of roughness changes on contaminant transport in sewers. Acta Hydrologica Slovaca, 21(2), 145-151. 2644-4690. DOI: https://doi.org/10.31577/ahs-2020-0021.02.0018

Publisher: Institute of Hydrology SAS, Dúbravská cesta 9, 841 05 Bratislava, Slovakia