Abstract: The 3-D flow fields of the round jets with pulsed jet blowing for mixing enhancement were simulated numerically. This work uses a technique for injecting high frequency and high intensity signals into subsonic shear layers for the purpose of jet mixing enhancement. The finite volume method, RNG k-ε turbulence model were employed to solve N-S equation. Numerical simulations of low Mach 0.23 and high Mach number 0.9 jets exhausting into fluid were conducted. Three cases are considered in detail: a unforced case and two cases that are forced with flapping modes at Strouhal numbers 0.2 and 0.4.These simulations show that pulsed jet blowing at either frequency causes the jet to expand rapidly in the plane parallel with the actuators and to contract in the plane perpendicular to the actuators, the intensity of motion and associated mixing are higher when the excitation Strouhal number is around 0.2, and small injection flow rates can provide tremendous increases in velocity decay rates.