UCL Discovery Stage
UCL home » Library Services » Electronic resources » UCL Discovery Stage

Large Eddy Simulation of Free Surface Flow Over Square Bars in Laminar, Transitional and Turbulent flows

Jalalabadi, R; Stoesser, T; (2022) Large Eddy Simulation of Free Surface Flow Over Square Bars in Laminar, Transitional and Turbulent flows. In: Ortega-Sanchez, M, (ed.) Proceedings of the 39th IAHR World Congress (Granada, 2022). (pp. pp. 3632-3641). International Association for Hydro-Environment Engineering and Research (IAHR) Green open access

[thumbnail of 06-01-004-138.pdf]
Preview
Text
06-01-004-138.pdf - Published Version

Download (18MB) | Preview

Abstract

Results of large-eddy simulations of laminar, transitional and turbulent free surface flow at constant Froude number over spanwise-aligned square bars are analyzed. Two different bar spacing corresponding to transitional and k-type roughness are selected. The water surface deformations include mild undulation in flow over transitional roughness and a distinct standing wave in flow over k-type roughness. The streamwise gradient of streamwise velocity in response to the k-type roughness contributes to the formation of standing wave at the water surface which is not present in transitional roughness. The friction coefficient in laminar and transitional flow are of the same order and significantly larger than that in turbulent flow. The large water surface deformation induces larger dynamic pressure in the bulk of the flow over k-type roughness than transitional roughness at all Reynolds number. In turbulent flows, the root-mean-square fluctuations of spanwise velocity and pressure have similar peak values under water surface over the two roughness types implying negligible effects of water surface deformations on these variables. Other velocity and pressure fluctuations, however, have different peak values under the water surface in flow over the two roughness. Instantaneous pressure fluctuations also undergoes large variations while these variations are larger in flow over k-type roughness. Turbulent and wake kinetic energy have similar distribution as the velocity fluctuations and are modulated under the standing wave. The friction factor decomposition reveals that the contribution of dispersive shear stress increases and that of Reynolds shear stress decreases by increasing bar spacing.

Type: Proceedings paper
Title: Large Eddy Simulation of Free Surface Flow Over Square Bars in Laminar, Transitional and Turbulent flows
Event: 39th IAHR World Congress
Location: SPAIN, Ctr Studies & Experimentat Publ Works, Spain Water, Granada
Dates: 19 Jun 2022 - 24 Jun 2022
ISBN-13: 978-90-832612-1-8
Open access status: An open access version is available from UCL Discovery
DOI: 10.3850/IAHR-39WC252171192022138
Publisher version: doi://10.3850/IAHR-39WC2521716X2022138
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Free surface flow, large-eddy simulation, rough-bed flow, turbulent flow, transitional flow, laminar flow
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Civil, Environ and Geomatic Eng
URI: https://discovery-pp.ucl.ac.uk/id/eprint/10199296
Downloads since deposit
133Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item