URBULENCE MODELLING OF OIL SLICK

he motion of a lock-release oil slick as an immiscible two-fluid gravity current is numerical studied by a finite difference algorithm based on the volume of fluid (VOF) method for the basic formulation and a rigid cover approximation for the open free surface. Detailed numerical simulation with careful model validation reveals the existance of turbulence and the adaptability of the renormalization group (RNG) model for the Reynolds-stress closure in the case of the oil slick. The evolution of turbulence kinetic energy and turbulent viscosity is characterised, and asymptotic self-similar spreading laws are well reproduced. The mechanism for the transition from an initial gravity-inertial phase to a second gravity-viscous phase is shown to be the relaminarization effect of the initially highly turbulent slick.