NUMERICAL-SIMULATION OF THE INSTABILITY OF AN INVISCID LIQUID JET IN A COFLOWING COMPRESSIBLE AIRSTREAM

The nonlinear interfacial instability of a liquid jet in a coflowing c ompressible airstream is studied numerically. A high-resolution scheme which has second-order accuracy in space and time is coupled with a L agrangian marker particle algorithm to visualize the large-scale motio n of the interfaces in compressible flow. A numerical algorithm based on an approximate equation of state of a compressible liquid is develo ped to allow this two-fluid system to be governed by the nonlinear uns teady Euler equations in conservative form. The initial growth of smal l disturbances given by the simulations agrees well with linear theory . The process of jet disruption in compressible flow is demonstrated t o consist of the formation of liquid spikes, interweaving of the gas a nd liquid and stretching and detachment of the liquid main center core .