The unsteady behavior of a flow driven by a jet suddenly injected into cells is investigated numerically by solving the axisymmetric two-dimensional compressible Navier-Stokes equations. The system of the calculation is a model of laser ablation of a certain duration followed by a discharging process through the exit hole at the downstream end of the cell. The parameters for the calculations are the diameter of the cell, the exit diameter of the cell and the duration of the injected jet. The

more »

... ocity monitored at the exit hole is used to evaluate the influence of the shape and the exit diameter of the cell on the shock wave, the plume, and their interactions. As a result, it was found that the position in which the shock wave converges and the focal point of the elliptical cell are almost the same for various parameters. The spreading shock wave that converged at the geometrical focal point reflects from the cell wall and this shock wave alternate between the jet injection and the cell exit. It was also found that the number of peaks and the maximum velocity downstream of the cell exit are roughly determined by the contour of the walls of the elliptical cell.