Evaluation of Effective Wall Roughness for 3D Computational Analysis of Open Channel Flow

개수로 흐름의 3차원 전산해석을 위한 유효 벽면거칠기 산정

  • 최준우 (한양대학교 토목공학과) ;
  • 백운일 (한양대학교 토목공학과) ;
  • 이상목 (극동건설(주) 토목기술팀) ;
  • 윤성범 (한양대학교 공학대학 토목.환경공학과)
  • Received : 2008.01.08
  • Accepted : 2008.09.01
  • Published : 2008.11.30

Abstract

In a numerical simulation of open channel turbulent flows using RANS (Reynolds averaged Navier-Stokes) equations model equipped with VOF (Volume of Fluid) scheme, the determination of wall roughness for wall function was studied. The roughness constant, based on the law-of-the-wall for flow on rough walls, obtained by experimental works for pipe flows is employed in general wall functions. However, this constant of wall function is the function of Froude number in open channel flows. Thus, the wall roughness should be determined by taking into account the effect of Froude number. In addition, the wall roughness should be corresponding to Manning's roughness coefficient widely used for open channels. In this study, the relation between wall roughness height as an input condition and Manning's roughness coefficient was investigated, and an equation for effective wall roughness height considering the characteristics of numerical models was proposed as a function of Manning's roughness coefficient.

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