Fig. 10 Transverse scour hole profles for six cases

본 소개 자료는 ‘Environmental Fluid Mechanics’에서 발행한 ‘Numerical simulation of local scour around the pier with and without airfoil collar (AFC) using FLOW-3D’ 논문을 기반으로 합니다.

Fig. 10 Transverse scour hole profles for six cases
Fig. 10 Transverse scour hole profles for six cases

1. 서론

  • 교각 주변의 국부 세굴(local scour)은 수리 구조물의 안전성에 중대한 영향을 미치는 요소이며, 교량 붕괴의 주요 원인 중 하나임.
  • 기존 연구에서는 다양한 세굴 저감 장치를 연구해 왔으며, 본 연구에서는 에어포일 컬러(Air-Foil Collar, AFC)의 효과를 평가하고자 함.
  • FLOW-3D를 이용하여 다양한 AFC 구성에서 세굴 깊이를 수치적으로 분석하고, 실험 결과와 비교하여 모델의 신뢰성을 검증함.

2. 연구 방법

FLOW-3D 기반 CFD 모델링

  • 난류 해석: Large Eddy Simulation (LES) 모델 적용.
  • 퇴적물 모델: van Rijn의 bed-load transport 모델 활용.
  • 격자 설정: 12.234백만 개의 격자로 구성된 nested mesh 사용.
  • 경계 조건:
    • 유입부: 일정한 유속(velocity inlet) 적용.
    • 유출부: 자유 배출(outflow) 조건 적용.
    • 벽면: No-slip 조건 적용.

3. 연구 결과

AFC 적용 유무에 따른 세굴 특성 비교

  • AFC가 없는 경우 최대 세굴 깊이: 6.33cm.
  • AFC가 적용된 경우 세굴 깊이 감소 효과:
    • dc1 (2b) 컬러 적용 시: 77.78% 감소.
    • dc1R (역방향 2b) 컬러 적용 시: 46% 감소.
    • dc2 (3b) 컬러 적용 시: 100% 감소 (세굴 없음).
    • dc1 (2b) 컬러를 하단부에서 y/2 높이에 적용 시: 11.12% 감소.
    • dc2 (3b) 컬러를 하단부에서 y/2 높이에 적용 시: 42.86% 감소.
  • 최대 세굴 깊이 및 세굴 형상 분석
    • AFC가 없는 경우, 세굴은 주로 교각 전면부에서 강하게 발생하며 후류(wake)에서 퇴적이 진행됨.
    • AFC 적용 시, 와류 강도가 감소하고 말굽 와류(horseshoe vortex) 및 후류 난류가 완화됨.
  • AFC의 위치 및 크기에 따른 효과 분석
    • dc2 (3b) 컬러를 교각 기초에 설치했을 때 세굴 방지가 가장 효과적.
    • dc1 (2b) 컬러의 경우 역방향(dc1R) 설치 시 세굴 감소 효과가 다소 감소.

4. 결론 및 제안

결론

  • AFC는 교각 주변 국부 세굴을 효과적으로 감소시킬 수 있는 구조적 솔루션임.
  • 3b 크기의 컬러(dc2)를 교각 기초에 설치하는 것이 가장 효과적인 세굴 방지 방법으로 확인됨.
  • LES 모델을 활용한 수치 시뮬레이션 결과가 실험 결과와 7% 이내의 오차를 보이며 높은 신뢰도를 가짐.

향후 연구 방향

  • 다양한 유속 및 침전 조건에서 추가 시뮬레이션 수행 필요.
  • 실제 현장 데이터를 기반으로 AFC의 장기적인 효과 검증.
  • AFC 형상 최적화를 위한 설계 연구 수행.

5. 연구의 의의

본 연구는 FLOW-3D를 활용하여 AFC의 적용 유무에 따른 교각 주변 국부 세굴 특성을 수치적으로 분석하고, 실험 데이터를 통해 모델 신뢰성을 검증하였다. 이를 통해 향후 교량 설계 시 AFC 적용을 고려한 세굴 방지 전략을 제안할 수 있는 실질적인 데이터를 제공한다.

Fig. 3 a Meshing around the geometry and b boundary conditions annotated
Fig. 3 a Meshing around the geometry and b boundary conditions annotated
Fig. 4 Scour hole profle from Melville and Raudkivi [16] and simulated results
Fig. 4 Scour hole profle from Melville and Raudkivi [16] and simulated results
Fig. 10 Transverse scour hole profles for six cases
Fig. 10 Transverse scour hole profles for six cases

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