عنوان مقاله [English]
Rivers affected by natural factors or human interventions are involved in Corrosion of bed and sides. One of the common methods in controlling and protecting riversides is the use of groin. Gabion groynes are a kind of spur dike. On the basis of hydrodynamic the contrast between gabion groin of river and the environmental fluid are complex and computing of the affected force on them are so important. If a real fluid, with a constant velocity, passes around a groine, there is a drag force due to fluid viscosity. Lee et al (2011) used the time average of Navier-Stokes equations and k-ε turbulent model to predict the flow around permeable pile groins to develop a 2-D numerical model. Their results indicated that the direction of the approaching flow is diverted by increasing the flow rate, which is an advantage to protect the river banks Duan and Nanda (2006) simulated the distribution of suspended sediment concentrations around a spur dike using a two-dimensional depth averaged hydrodynamic model and solution of two-dimensional Navier-Stokes equations. Azinfar and Kells (2009) studied the flow around a single spure dike with different sizes using measurement flow and depth and using momentum equation. They resultes that an increase in the blockage due to the spur dike plate is the main parameter responsible for an increase in the spur dike drag coefficient, hence the associated flow resistance. The effect of porosity percentage of these porous groines in channels and rivers is not carefully investigated on how the pressure and drag force on these groin is distributed. Therefore, the necessity of studies in this field is observed.