Numerical simulation of the lagrangian SVP drifter and investing the effect of the geometry’s characteristic on its performance

In this paper, different types of SVP drifters are analyzed by using a three-dimensional computational environment to investigate the effect of geometrical characteristics of a Lagrangian drifter on its performance in the flow conditions in the Persian Gulf. By observing and examining the shape of the flow around the lateral and internal cavities of the Drago, it is concluded that the presence of cavities on the Drago causes a uniform distribution of compressive and viscous forces on the surface of the Drago. If a holeless cylinder is used as a Drago, a significant reduction in drag and slip coefficient is seen, especially at high-velocity currents. Increasing the number of holes on the Drago will not have much effect on the drifter performance and the most effective factors are changing the diameter and height of the Drago. Thus, a 30% increase in the diameter of the Drago increases the drag coefficient by 90%. In general, by examining the contour and flow velocity vector, it is found that the geometry design of Drago Drifter should be such that behind the drag, the smaller radius flow vortices are formed, and these small vortices cause uniform distribution of hydrodynamic forces on the surface of the Drago and prevent the drifter from slipping in sudden changes in current velocity.