Despite a lot of experimental investigations, the effect of airfoil serrations on the reduction of discrete frequency noise (DFN) is not fully understood. We apply the large-eddy simulation (LES) to the turbulent flow around the NACA0012 airfoil without angle of attack in a uniform stream. In this case, a major source of aerodynamic noise is quasi two-dimensional spanwise vortices, which take place near the trailing edge. We therefore investigate the effect of serration in the trailing edge side. The depth of the serration is 10% of chord length. To take into account the weak compressibility at low Mach number, we made a particular modification to the pressure equation. One equation dynamic model for the subgrid scale stress is used for LES. These techniques have originally been developed in our research group. The serration successfully reduced the pressure fluctuations on the surface of the airfoil near the trailing edge. The observed structure of the density variation suggests that this modification contributes to the reduction of sound source.

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