Journal of Korean Society of Coastal and Ocean Engineers (한국해안·해양공학회논문집)

Korean Society of Coastal and Ocean Engineers (한국해안·해양공학회)
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Effect of Wall Thickness of Perforated Wall with Vertical Slits on Wave Reflection and Transmission

연직 슬릿 유공벽의 벽두께가 파랑 반사 및 전달에 미치는 영향

  • Kwon, Kab Keun (Industry-University Cooperation Foundation, ERICA Campus, Hanyang University) ;
  • Lee, Jong In (Department of Marine and Civil Engineering, Chonnam National University) ;
  • Yoon, Sung Bum (Dept. of Civil, Env. and Plant Engrg., ERICA Campus, Hanyang University)
  • 권갑근 (한양대학교 산학협력단) ;
  • 이종인 (전남대학교 해양토목공학과) ;
  • 윤성범 (한양대학교 건설환경플랜트공학과)
  • Received : 2014.10.11
  • Accepted : 2014.11.19
  • Published : 2014.12.31
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Abstract

The reflection and transmission coefficients of waves due to perforated wall are mainly determined by both the porosity and wall thickness of the perforated wall and the period and nonlinearity of incident waves. Among them the wall thickness is very important because it affects the head loss coefficient and the inertia length of the wall. However, by employing the head loss coefficient derived for sharp crested orifice, the previous researches have neglected, or incorrectly considered the effect of wall thickness on the head loss coefficient. Even though it is considered, the effect of the inertia length is neglected in some empirical formulae. Thus, the effect of wall thickness on the reflection and transmission coefficients of waves is not properly considered. In this study comprehensive experiments are conducted for the perforated walls with various thicknesses, and the results are compared with those predicted by the empirical formulae. As a result it is found that the existing formulae can not properly consider the effect of wall thickness, and it is confirmed that a new formula which can correctly consider the effect of wall thickness on the head loss coefficient is necessary.

유공벽에 의한 파의 반사율과 투과율은 주로 유공벽의 공극률과 벽두께 그리고 입사파의 주기 및 비선형성에 의해 결정된다. 이중에서 벽두께는 유공벽의 수두손실계수와 관성저항길이에 영향을 미치므로 매우 중요하다. 그러나 기존의 연구에서는 예연 오리피스의 수두손실계수를 사용함으로써 수두손실계수에 미치는 벽두께 효과를 무시 또는 부정확하게 고려하였거나, 벽두께가 수두손실계수에 미치는 영향은 고려하였더라도 관성저항 길이를 무시함으로써 벽두께가 유공벽의 반사율과 투과율에 미치는 영향이 적절히 고려되지 못 하였다. 따라서 본 연구에서는 다양한 두께의 유공벽을 제작하여 파의 반사율 및 투과율 측정 수리실험을 수행하였으며, 그 결과를 기존의 해석해에 의한 값과 비교하였다. 비교결과 기존의 해석해 들이 벽두께의 효과를 적절히 반영하지 못하고 있음을 확인하였으며, 벽두께 효과를 정도 높게 고려할 수 있는 새로운 수두손실계수 산정식이 필요함을 확인하였다.

Keywords

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