Numerical study on evolution of axisymmetric natural supercavitation influenced by turbulent drag-reducing additives

This paper attempts to investigate the effect of turbulent drag-reducing additives during the evolution process of natural supercavities. The finite volume method was adopted to numerically simulate the development process of natural cavitating flow. Specifically, in order to characterize the rheological property of the drag-reducing solution, the Cross viscosity equation together with a decreased surface tension coefficient were employed. Firstly, steady numerical simulation is performed on the characteristics of supercavitation in water and drag-reducing solutions to verify the accuracy of the numerical procedure. Subsequently, supercavity-configuration and drag resistance varying with time were intensively analyzed. The results indicate that, at the same instant, the cavity has a larger size in length and diameter when handling drag-reducing solutions than the water case. Meanwhile, the drag felt by the underwater projectile maintains smaller in drag-reducing solution cases. Another interesting phenomenon is that both in water and drag-reducing solution, the sizes of the cavities increase first and then decrease to a constant value; in addition, the resistances decrease first with time, and then increase to a stable state. (C) 2016 Elsevier Ltd. All rights reserved.