재순환유동 예측을 위한 κ-ε 난류모델 개선에 대한 연구

Abstract

The standard <TEX>${\kappa}-{\varepsilon}$</TEX> and realizable <TEX>${\kappa}-{\varepsilon}$</TEX> models are adopted to improve the prediction performance on the recirculating flow. In this paper, the backward facing step flows are used to assess the prediction performance of the recirculation zone. The model constants of turbulence model are obtained by the experimental results and they have a different value according to the flow. In the case of an isotropic flow situation, decaying of turbulent kinetic energy should follow a power law behavior. In accordance with the power law, the coefficients for the dissipation rate of turbulent kinetic energy are not universal. Also, the other coefficients as well as the dissipation coefficient are not constant. As a result, a suitable coefficients can be varied according to each of the flow. The changes of flow over the backward facing step in accordance with model constants of the <TEX>${\kappa}-{\varepsilon}$</TEX> models show that the reattachment length is dependent on the growth rate(<TEX>${\lambda}$</TEX>) and the <TEX>${\kappa}-{\varepsilon}$</TEX> models can be improved the prediction performance by changing the model constants about the recirculating flow. In addition, it was investigated for the curvature correction effect of the <TEX>${\kappa}-{\varepsilon}$</TEX> models in the recirculating flow. Overall, the curvature corrected <TEX>${\kappa}-{\varepsilon}$</TEX> models showed an excellent prediction performance.