PREDICTION OF THE MOST EFFECTIVE PLACEMENT OF GROYNES AT A RIVER BEND USING ANSYS FLUENT

Abstract

In a meandering river the most critical section of the river is when it changes its curvature, at this section complex flow takes place, also the additional forces like the centrifugal force that come into play due to the curvature make the bank protection against scouring essential. The influence factors of spur are largely related to the stream characteristics, hydrologic variables, hydraulic characteristics and local variables. So the analysis considering all the involved factors becomes very extensive. There are very few studies that concentrate on the analysis of flow in a channel bend, owing to the complexities. Simulating the curvature and river conditions in a flume is also tough, fortunately making use of computational dynamic software help in simulation studies. In this study groynes at different positon on the channel bend are analyzed using ANSYS Fluent software. The turbulence model used was standard k-epsilon model for the flow. Four different lengths of spurs were taken i.e. 2.5m, 3m, 3.5m, 4m.The groynes were placed at six different positions. Furthermore three different approach velocities were taken i.e. 2.6m/s, 2m/s and 1.4m/s. So in total 72 different combinations of cases were undertaken and the results analyzed. The tip velocities, protected length and bed shear stress were compared for different positions of groyne. Multiple linear regression has been used to see the relationship and correlation between the maximum bed shear stress, tip velocity, protected length, groyne length and position of groyne. The most effective position of the groyne among the six cases was suggested in this study, also suggestions were made for the appropriate length of groyne.