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Estimation of Friction Coefficient in Permeability Parameter of Perforated Wall with Vertical Slits  

Kim, Yeul-Woo (R&D Center, Kunil Engineering Co., Ltd.)
Suh, Kyung-Duck (Department of Civil & Environmental Engineering, Seoul National University)
Ji, Chang-Hwan (Department of Civil & Environmental Engineering, Seoul National University)
Publication Information
Journal of Korean Society of Coastal and Ocean Engineers / v.22, no.1, 2010 , pp. 25-33 More about this Journal
Abstract
The matching condition at a perforated wall with vertical slits involves the permeability parameter, which can be calculated by two different methods. One expresses the permeability parameter in terms of energy dissipation coefficient and jet length at the perforated wall, being advantageous in that all the related variables are known, but it gives wrong result in the limit of long waves. The other expresses the permeability parameter in terms of friction coefficient and inertia coefficient, giving correct result from short to long waves, but the friction coefficient should be determined on the basis of a best fit between measured and predicted values of such hydrodynamic coefficients as reflection and transmission coefficients. In the present study, an empirical formula for the friction coefficient is proposed in terms of known variables, i.e., the porosity and thickness of the perforated wall and the water depth. This enables direct estimation of the friction coefficient without invoking a best fit procedure. To obtain the empirical formula, hydraulic experiments are carried out, the results of which are used along with other researchers' results. The proposed formula is used to predict the reflection and transmission coefficients of a curtain-wall-pile breakwater, the upper part of which is a curtain wall and the lower part consisting of a perforated wall with vertical slits. The concurrence between the experimental data and calculated results is good, verifying the appropriateness of the proposed formula.
Keywords
Friction coefficient; perforated wall; permeability parameter; vertical slit;
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  • Reference
1 Bennett, G.S., McIver, P. and Smallman, J.V. (1992). A mathematical model of a slotted wavescreen breakwater. Coastal Eng., 18,231-249.   DOI   ScienceOn
2 Sollitt, C.K. and Cross, R.H. (1972). Wave transmission through permeable breakwaters. Proc., 13th Int. Conf. on Coastal Eng., ASCE, 3, 1827-1846.
3 Isaacson, M., Premasiri, S. and Yang, G. (1998). Wave interactions with vertical slotted barrier. J. Waterw., Port, Coastal, and Ocean Eng., 124, 118-126.   DOI   ScienceOn
4 Li, Y., Liu, Y. and Teng, B. (2006). Porous effect parameter of thin permeable plates. Coastal Eng. J., 48, 309-336.   DOI
5 Mei, C.C. (1983). The applied dynamics of ocean surface waves, Wiley, Newyork.
6 Park, W.S., Kim, B.H., Suh, K.D. and Lee, K.S. (2000). Scattering of irregular waves by vertical cylinders. Coastal Eng. J., 42, 253-271.
7 Press, W.H., Teukolsky, S.A., Vetterling, W.T. and Flannery, B.P. (1992). Numerical recipes in FORTRAN: The art of scientific computing, Cambridge University Press, Cambridge, U.K.
8 Willmott, C.J. (1981). On the validation of models. Physical Geography, 2, 184-194.
9 Hossain, A., Kioka, W. and Kitano, T. (2001). Transmission of long waves induced by short-wave groups through a composite breakwater. Coastal Eng. J., 43, 83-97.   DOI
10 Suh, K.D., Shin, S. and Cox, D.T. (2006). Hydrodynamic characteristics of pile-supported vertical wall breakwaters. J. Waterw.,Port, Coastal, and Ocean Eng., 123(3), 118-126.
11 Zhu, S. and Chwang, A.T. (2001). Analytical study of porous wave absorber. J. Eng. Mech., 127, 326-332.   DOI   ScienceOn
12 Yu, X. (1995). Diffraction of water waves by porous breakwaters. J. Waterw., Port, Coastal, and Ocean Eng., 121, 275-282.   DOI   ScienceOn
13 서경덕, 지창환, 김열우 (2008). 연직 슬릿 유공벽의 투수계수 계산방법의 비교. 제 5회 한국유체공학학술대회 논문집, 제주, 506-509.
14 Kakuno, S. and Liu, P.L.-F. (1993). Scattering of water waves by vertical cylinders. J. Waterw., Port, Coastal, and Ocean Eng., 119(3), 302-322.   DOI   ScienceOn
15 Suh, K.D., Park, W.S. and Park, B.S. (2001). Separation of incident and reflected waves in wave-current flumes. Coastal Eng., 43,149-159.   DOI   ScienceOn
16 Hagiwara, K. (1985). Analysis of upright structure for wave dissipation using integral equation. Proc., 19th Int. Conf. on Coastal Eng., ASCE, 3, 2810-2826.
17 Kim, B.H. (1998). Interaction of waves, seabed and structures. PhD dissertation, Seoul National Univ., Seoul. Korea., 5, 142-146.
18 Losada, I.J., Losada, M.A. and Baquerize, A. (1993). An analytical method to evaluate the efficiency of porous screens as wave dampers. Applied Ocean Research, 15, 207-215.   DOI   ScienceOn
19 조일형, 김남형 (2002). 직접 슬릿판에 의한 반사율과 투과율 해석. 한국해안해양공학회지, 16(3), 1-7.
20 Mei, C.C., Liu, P.L.-F. and Ippen, A.T. (1974). Quadratic loss and scattering of long waves. J. Waterw., Harbors Coastal Eng. Div., Am. Soc. Civ. Eng., 100, 217-239.
21 Suh, K.D., Son, S.Y., Lee, J.I. and Lee, T.H. (2002). Calculation of irregular wave reflection from perforated-wall caisson breakwaters using a regular wave model. Proc. 28th Conf. on Coastal Eng., 3, 1709-1721.