This paper describes flow structures of two interacting free jets expanded from uniform sonic nozzles into a stagnant ambient gas region. The Euler equations are numerically solved using a TVD (Total Variation Diminishing) scheme developed by Chakravarthy and Osher. First, a choked underexpanded supersonic single free jet is investigated in detail in the context of continuum ideal gas dynamics. By comparing the numerical results so obtained with the experimental ones it is confirmed that the present scheme is reliable. Second, the effect of the distance between the nozzle centerlines on the flow field of the two jets interacting with each other is examined from an analytical standpoint. Thereby, we find that a perfectly time-converged numerical solution is not reached at all, even at t→∞ (t : time). Rather, the solution may be regarded as quasi-steady or slightly oscillatory. Characteristic shock systems, density and pressure distributions of the interacting two free jets are quantitatively discussed in view of the numerical experiments. Also, a few fresh findings are described
