균일유동에 수직인 2차원 스크린 후류의 점성유동에 관한 수치적 연구

Numerical Study on Viscous Wakes of Two-Dimensional Screens Normal to the Uniform Stream

본 연구에서는 난류유동이론을 적용하여 2차원 스크린의 후류에 관한 유동특 성을 연구하였다. 이를 위해 적합한 난류모델 및 스크린의 존재를 고려한 수치해석 방법을 연구하였다. 스크린의 저항이 커서 스크린 하류유동이 역류가 되는 경우도 포함하였다.

Viscous flows through a screen normal to an uniform flow are numerically simulated. A .kappa.-.epsilon. model is adopted for evaluation of the Reynolds stresses. The existence of a screen is regarded as extra sources in the momentum equations. The amount of extra sources is related to the resistance coefficient and the refraction coefficient of the screen. Flows are numerically simulated for various resistance coefficients and heights of the screen and Reynolds numbers. The present method has been verified to reasonably simulate viscous wakes and shear layers of the screen, for which the inviscid theory is quite limitted. As the fluids approach the screen, the velocity is reduced and the pressure is raised to satisfy the Bernoulli equation. After passing the screen, the velocity shows its minimum value at the down-stream, but static pressure is slowly recovered. A detached separation-bubble from the screen appears as the resistance coefficient is increased to a certain level. Such results are qualitatively in agreement with limitted experimental data available. The turbulent kinetic energy shows its maximum value at further down stream and decrease thereafter.