抄録
Unsteady numerical simulation is carried out for 3D velocity field of a turbulent trailing vortex using non-linear κ-ε model. The general features of vortex decay as well as the different time periods of turbulence growth/decay captured in present simulation are discussed. The self similarity in the radial distribution of tangential velocity and circulation profiles are examined for trailing vortex. The simulation is also performed using standard κ-ε model, and comparison is shown with non-linear model. Since the rotational effects of vortex were not captured by a standard κ-ε model, it predicted extremely rapid and strong turbulence growth and causes a rapid decay of tangential and axial velocities. However, the non-linear model shows good agreement with previous DNS data. It is observed that the decay rate of axial velocity is much higher than tangential velocity. Five different time zones are observed in the growth/decay process of turbulent kinetic energy. In the matured stage of a trailing vortex, the turbulent normal stresses show two types of anisotropic behavior depending on the radial distance.
