Porous Triangular Structure's Drag Coefficient as a Submerged Obstruction in Open Channels

Ira Widyastuti; Riswandy Loly Paseru

doi:10.48084/etasr.11115

Authors

Ira Widyastuti Department of Civil Engineering, Faculty of Engineering, Cenderawasih University, Papua 99332, Indonesia
Riswandy Loly Paseru Department of Civil Engineering, Faculty of Engineering, Cenderawasih University, Papua 99332, Indonesia

Volume: 15 | Issue: 4 | Pages: 24532-24540 | August 2025 | https://doi.org/10.48084/etasr.11115

Received: 24 March 2025 | Revised: 5 May 2025 and 11 May 2025 | Accepted: 15 May 2025 | Online: 31 May 2025

Corresponding author: Ira Widyastuti

Abstract

This research aims to dampen energy without causing significant erosion around the obstacle models. Experiments were conducted on a square channel using three models of triangular plates (MP1, MP2, MP3) with a 30° slope and different levels of porosity (0, 10, and 15%). The flow channels around the energy obstacles were measured to assess different areas of the obstacle structure, depending on the channel characteristics and Reynolds number, using the drag coefficient (C_D). Frictional forces were attributed to shear stress on the surface of solid objects moving through a viscous fluid. The results showed that the effect of energy-absorbing porous materials on reducing flow velocity before passing through the obstacles varied across models: a 31.42% decrease in MP1, a 9.27% increase in MP2, and a 32.92% increase in MP3. The average flow velocity after passing through MP1, MP2, and MP3 increased significantly by 37.80%, 25.00%, and 43.85%, respectively. The drag coefficient (C_D) of porous obstacles was calculated by comparing the measured drag coefficients across models, resulting in a similar average across models, amounting to 4.82 (MP1), 4.03 (MP2), and 3.76 (MP3). The Reynolds number was 3.7x10⁵ – 7.4x10⁵, indicating the presence of laminar, transitional, or turbulent boundary layers.

Keywords:

porous triangle structure, drag coefficient, flow reduction

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