Formation and Development of Spreading Gravity Currents

摘要

The formation and development of gravity currents spreading out in all directions is investigated by the experiment and by the computation. A finite volume of fluid is released instantaneously in another fluid of slightly different density in a large area. Visualization experiments were made with dye to trace the head of the gravity currents. A cylindrical box model is introduced to describe different stages of a spreading gravity current on the basis of energy argument. The computation is made to study the flow structure of the spreading gravity current. The incompressible Navier-Stokes equation for an inhomogeneous fluid together with the transport equation for solute is solved by the finite volume method. The results indicate that the different stages predicted by the box model exist in this type of radially spreading gravity current. At the first stage the released fluid spreads at a constant speed, it slows down in self-similar stage, and then it decelerates further in the viscous stage.