Tebing sungai simpan terdedah kepada hakisan akibat perubahan arah aliran. Halaju air maksimum berlaku di bank cekung akibat daya sentrifugal. Entrainment sedimen akibat hakisan meningkatkan beban sedimen di sungai. Tahap endapan yang berlebihan mengurangkan kualiti air serta kualiti habitat ekosistem air tawar. Weird Bendway yang pelbagai struktur dinding batu yang didirikan dari katil sungai diperkenalkan untuk mengurangkan hakisan bank cekung. Mekanisme bendung weir mengarahkan arah air ke arah aliran tegak aliran aliran untuk melindungi tebing sungai. Pemodelan berangka tiga dimensi dijalankan dengan menggunakan perisian Dynamic Fluid Dinamik, Flow 3D ® oleh Flow Science untuk menilai keberkesanan bendung weir. Model Re-Normalization (RNG) k-epsilon yang merupakan model pergolakan digunakan untuk pemodelan dalam Aliran 3D untuk kajian ini. Keputusan dianalisis secara kualitatif oleh skala warna menunjukkan model dengan dipasang bendway weir pengurangan kelajuan di luar bank dan tekanan ricih yang berlebihan di pelbagai titik bank sungai. Bendway lokasi optimum juga diramalkan dengan membandingkan pelbagai pilihan pengaturan berdasarkan magnitud halaju dan tekanan ricih yang berlebihan. Kesimpulannya adalah bendway weir yang berkesan untuk mengurangkan halaju dan tekanan ricih di tebing sungai cekung.
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Concave river bank is prone to erosion due to the flow direction changes. Maximum water velocity is occurring at concave bank due to centrifugal force. Entrainment of sediment due to erosion increases sediment loads in river. Excess sediment level reduces quality of water as well as quality of fresh water ecosystems habitats. Bendway weirs which are various stone wall structures erected from river bed was introduced to reduce erosion of concave bank. The mechanism of bendway weir is redirecting the water direction into perpendicular direction of stream flow to protect river bank. Three dimensional numerical modeling is carried out by using Computational Fluid Dynamic software, Flow 3D ® by the Flow Science to evaluate the effectiveness of bendway weir. Re-Normalisation Group (RNG) k-epsilon model which is a turbulence model is adopted for modeling in Flow 3D for this study. Results is analyzed qualitatively by colour scales shows that model with installed bendway weir gain reduction of velocity at outer bank and excess shear stress at various point of river bank. Bendway weir optimum locations are also predicted by comparing various arrangement options based on velocity magnitude and excess shear stress. Conclusion is bendway weir is effective to reduce velocity and shear stress at concave river bank.
Prediction of flow pattern at river bend using flow 3d modeling for bendway weir / Lim Yeong Shen