Experimental investigations on an influence of density difference to the mixing process are presented. Acoustic excited round jet of the air or CO_2 is issued from a round pipe and mixed with the co-flowing air. The motion of the jet is visualized in the two-dimensional cross-section using a laser tomography method with Ar^+laser and high-speed video camera. Time-variation width of the jet is measured from visualized images and the attractor is made. The attractors show typical shapes corresponding with various jet motions. The similar attractor is obtained for CO_2 jet, if the momentum of CO_2 jet is set as that of air jet.
