NUMERICAL ANALYSIS OF LOCAL SCOURING BY SEPARATION VORTEX AROUND LOW SLOPE REVETMENT

Abstract

Since a local scouring around spur-dikes or a groin decreases the stability of these structures, it is a very important problem on disaster prevention. Now, in the Meghna river in Bangladesh, the local scouring around the groin in the left bank of the just upstream of the Meghna bridge poses the problem. The feature of this local scouring is that the scouring hole is formed not around the upstream edge of the groin but in the more downstream by the influence of the low slope revetment. In this paper, we aim at the elucidation of the mechanism of this local scouring and discuss this phenomenon by the numerical analysis based on MacCormack scheme to the model river. The flow field is analyzed by 2-D and 3-D model, and the flow structure is discussed. Moreover, the local scouring is analyzed by 2-D model which can be applied to the bed evolution due to both bed and suspended loads, and the scouring process is discussed.