Laboratory study of the effect of vegetation arrangement and density on flow resistance coefficient

Subject Areas : Marine structures

سمیرا سلمان زاده ¹ , منوچهر فتحی مقدم ² , جواد احدیان ³ , سید محسن ساجدی ⁴

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Received: 2022-05-08 Accepted : 2022-08-01 Published : 2022-08-22

Keywords: تراکم, Staggered arrangement, Resistance coefficient, flexible vegetation, drag force, ضریب مقاومت, آرایش زیگزاگی, پوشش گیاهی انعطاف‌پذیر, نیروی درگ,

Abstract :

This paper has been done by considering the hydraulic conditions of the river flow and the morphological conditions of the vegetation along the river and floodplain. The hydrodynamic drag force was measured directly by use of loadcell in the presence of flexible vegetation. Accordingly, all experiments were performed in a flume named "knife edge flume" with 8.3 m length, 0.8 m width and a 0.55 m height. Flexible non-submerged vegetation models with 3 densities (30, 50 and 100%) and staggered arrangement in three relative water depths (0.6, 0.8 and 1) were tested. In this study, vegetation density changed with increasing distance and leaf area of models. The results showed that the drag force significantly depends on the density of vegetation as one of the measurable morphological features of the plant. Density results can be used as a useful criterion in estimating the resistance due to the presence of plant roughness in the river.

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