비정상 3차원 Navier-Stokes 식을 이용한 원형실린더 주위의 공력음향해석

Abstract

The effort aero-acoustic is coming to be various recently from all fields. Aerodynamic noise that happen in unsteady flow of vortex or effort noise that happen in jet flow does not expect by causing degradation and instability by provoking a lot of shocks. Specially, the oscillation vibration of shock wave happens by flow and interaction between acoustic. Theoretical and analytic method in the past. However, could plan interference action directly mutually between flow and sound because computer technology such as latest parallel processing technique uses computing effort sound developing greatly. To analysis aero-acoustic needs to a high order and resolution scheme. It is used to capture the aero-acoustic wave because acoustic energy is much smaller than flow energy. An optimized compact finite scheme used to spatial differentiation. The fourth order Runge-Kutta method is used for time integration. A generalized characteristic boundary condition applied to reduce non-physical reflection of acoustics wave at the far-filed boundary. The artificial dissipation model is important for numerical computation for the shock in the flow and acoustic. The adaptive nonliner artificial dissipation model consisted of two terms. first, A 4th-order selective background smoothing term for acoustics and the other term is 2nd-order well established terms for the shock. This method is good result of acoustic wave in present computation. Aero-acoustics computation needs to long time calculation. Numerical calculations were performed by different type parallel processing with time discretizations carried out by the 4th-order Runge-Kutta method. The circular cylinder diameter is 1 and far-filed condition is 40 from cylinder. The Mach number and the Reynolds number were 0.3 and 300, respectively. It is found that Laminar Reynolds number range is appear as phenomenon of acoustics wave and mutually between flow and acoustics at three dimensional circular cylinder.