TELEMAC-2D를 적용한 개수로 분류부 유량비 변화에 의한 흐름특성 분석

Numerical analysis of flow characteristics at the bifurcation channel by changing of discharge ratio using TELEMAC-2D

Abstract

본 연구에서는 분류부 흐름에 대한 TELEMAC-2D 2차원 수치모형의 적용성을 검증하고, 수치실험을 통한 분류유량비 계산식의 비교분석, 분류유량비 변화에 따른 분류부 흐름특성 변화를 분석하였다. 본 수치모형은 분류부 수심평균 유속분포와 수위에 대해 실내실험결과와 잘 일치하는 결과를 나타냈다. 주수로의 하류방향 관성력과 모멘트가 감소하면 분류유량비가 증가하게 되고, 분류수로에서 상대적인 고유속 분포구간은 넓어지며, 분류수로 주흐름의 역방향 유속은 감소한다. 분류유량비가 증가할수록 분류수로 내 흐름분리구역 규모는 감소하며, 흐름분리구역 규모 산정시 유선분포 작도뿐만 아니라 종방향 프루우드 수가 $Fr{\approx}0$이 되는 지점 확인으로 더 명확하게 산정할 수 있다.

This study investigates the flow characteristics, such as velocity distributions, size and location of recirculation zone, longitudinal flow change rates, and bifurcation discharge ratio in the bifurcation channel by TELEMAC-2D, a 2D numerical model. The numerical model is validated by previous experimental results and the numerical results are in relatively good agreement with the experimental results, such as the water surface elevation and velocity distribution in the channels. As the inertial force and moment in the main channel decrease, the bifurcation discharge ratio increases, and the relative high velocity distribution becomes wider and the reverse velocity of the main stream decreases in the branch channel. As the bifurcation discharge ratio increases, the size of the recirculation zone in the branch channel decreases and it can be more clearly calculated by determining the point where the longitudinal froude number $Fr{\approx}0$ as well as drawing the distribution of the streamline distribution.

Fig. 1. Flow patterns (Neary and Sotiropoulos, 1996)

Fig. 2. Experimental set-up (Shettar and Murthy, 1996)

Fig. 3. Depth-averaged velocity distribution

Fig. 4. Water surface profiles

Fig. 5. Measurement sections for the experiments

Fig. 6. Limitations of F_2H and Q_r (Hsu et al., 2002)

Fig. 7. Comparison of discharge ratio (Q_r)

Fig. 8. 2-Dimensional computed streamlines pattern

Fig. 9. Contraction coefficient in the branch channel

Fig. 10. Streamlines distributions

Fig. 11. Depth-averaged velocity distribution

Fig. 12. Froude number distributions

Fig. 13. Longitudinal froude number in the branch channel

Table 1. Flow conditions for physical experiments

Table 2. Flow conditions for physical experiments

Table 3. Flow conditions for numerical experiments