突発噴流の数値解析

抄録

The starting jet flow from a large chamber with a constant pressure is simulated by solving full Navier-Stokes equations with primitive variables. The growth and development processes of a vortex roll up are visualized using marker particles and related to velocity and pressure fields which are difficult to obtain experimentally. The main results can be summarized : (1) a short period after starting, the isobaric pattern is a concentric circle centered at the exit slit, and the fluid issues radially from the slit ; (2) as time elapses, the separated layer initiates rolling up to a vortex with a local low-pressure area ; (3) the developing vortex is transferred downstream at a longitudinal velocity along the separated layer ; (4) at a certain lateral section, the situation is unsteady as the vortex approaches and is carried downstream. When the vortex is carried far downstream, the flow tends to steady ; (5) in the vortex area, the isobaric pattern is concentric where the fluid particles are vortically entrained.