Volume 8 -                   ijmt 2017, 8 - : 15-24 | Back to browse issues page

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1- PhD Candidate Faculty of maritime engineering
2- Associate professor Faculty of maritime engineering
Abstract:   (553 Views)
Effect of air cushion layer right before impact of a rigid body onto water surface has been investigated in this paper. The study is mainly focused on evaluation of cushioning pressure and the resulting free surface elevation. The air flow is assumed to be an irrotational flow which is governed by Laplace equation. The air problem and the resulting response of the water free surface are supposed to be weakly coupled because of very low air pressure. Integral equation for each medium has been numerically solved separately using boundary element method. The problem is assumed to be unsteady with a constant body speed. The numerical results have been also compared with analytical method which shows a fair agreement. Results show that the geometry of impacting body and particularly its bluntness are the primary affecting parameter which can dramatically influence the free surface profile and air pressure. Such a behavior has been observed for two different geometries, ellipse and wedge section, having identical breadth.
Full-Text [PDF 952 kb]   (106 Downloads)    
Type of Study: Research Paper | Subject: Ship Hydrodynamic
Received: 2017/03/11 | Accepted: 2017/11/25

1. Verhagen, J.H.G., (1967), The impact of a flat plate on a water surface, Ship Res., Vol. 11, p.211-233.
2. Wilson, S.K., (1991), A mathematical model for the initial stages of fluid impact in the presence of a cushioning fluid layer, Engineering Mathematics, Vol. 25, p. 265-285 [DOI: 10.1007/BF00044334]
3. Hicks, P.D., Ermanyuk, E.V., Gavrilov, N.V. and Purvis, R., (2012), Air trapping at impact of a rigid sphere onto a liquid, Fluid Mechanics, Vol. 695, p. 310-320. [DOI: 10.1017/jfm.2012.20]
4. Hicks, P. and Purvis, R., (2011), Air cushioning in droplet impacts with liquid layers and other droplets, physics of fluids, 23(6). [DOI: 10.1063/1.3602505]
5. Tran, T., de Maleprade, H., Sun, C. and Lohse, D., (2013), Air entrainment during impact of droplets on liquid surfaces, Fluid Mechanics, Vol. 726. [DOI: 10.1017/jfm.2013.261]
6. Worthington, A.M., (1908), A Study of Splashes, Longmans, Green.
7. Thoroddsen, S.T., Etoh, T.G., Takehara, K., Ootsuka, N. and Hatsuki, Y., (2005), The air bubble entrapped under a drop impacting on a solid surface, Fluid Mechanics, Vol. 545, p. 203-212. [DOI: 10.1017/S0022112005006919]
8. Marston, J.O., VAKARELSKI, I.U., THORODDSEN, S.T., (2011), Bubble entrapment during sphere impact onto quiescent liquid surfaces, Fluid Mechanics, Vol. 680, p.660-670. [DOI: 10.1017/jfm.2011.202]
9. Von Karman, T., (1929), The impact on seaplane floats during landing, N.A.C.A.T.N. No. 321.
10. Wagner, H., (1931), Phenomena associated with impact and sliding on liquid surfaces, N.A.C.A. Translation 1366.
11. Chuang, S.L., (1970), Investigation of Impact of Rigid and Elastic Bodies with Water, Management Information Services.
12. Nethercote, W.C.E., Mackay, M. and Menon, B., (1986), Some warship slamming investigations, D.R.E.A. Technical Memorandum 86/206.
13. Okada, S. and Sumi, Y., (2000), On the water impact and elastic response of a flat plate at small impact angles, Journal of Marine Science and Technology, Vol.5, p. 31-39. [DOI: 10.1007/s007730070019]
14. Ermanyuk, E.V. and Ohkusu, M., (2005), Impact of a disk on shallow water, Fluids and Structures, Vol.20, p. 345-357. [DOI: 10.1016/j.jfluidstructs.2004.10.002]
15. Huera-Huarte, F.J., Jeon, D. and Gharib, M., (2011), Experimental investigation of water slamming loads on panels, Ocean Engineering, Vol.38, p. 1347-1355.
16. Lewison, G.R.G. and Maclean, W.M., (1968), On the cushioning of water impact by entrapped air, Ship Res., Vo.12, p.116-130. [DOI: 10.1016/j.oceaneng.2011.06.004]
17. Lewison, G.R.G., (1970), On the reduction of slamming pressures, Trans. R.I.N.A., Vol. 112, p. 285-306.
18. Asryan, N.G., (1972), Solid plate impact on surface of incompressible fluid in the presence of a gas layer between them, Izv. Akad. Nauk Arm. SSR Mekh, Vol. 25, p. 32-49.
19. Hicks, P. and Purvis, R., (2010), Air cushioning and bubble entrapment in three-dimensional droplet impacts, Fluid Mechanics, Vol. 649, p.135-163. [DOI: 10.1017/S0022112009994009]
20. Bouwhuis, W., van der Veen, R.C.A., Tran, T., Keij, D. L., Winkels, K.G., Peters, I.R., van der Meer, D., Sun, C., Snoeijer, J.H. and Lohse, D., (2012), Maximal Air Bubble Entrainment at Liquid-Drop Impact, PHYSICAL REVIEW LET TE RS, PRL 109, 264501 [DOI: 10.1103/PhysRevLett.109.264501]
21. Yousefnezhad, R. and Zeraatgar, H., (2014), A parametric study on water-entry of a twin wedge by boundary element method, J Mar Sci Technol, vol. 19, p. 314-326. [DOI: 10.1007/s00773-013-0250-1]
22. Katsikadelis, J.T., (2002), BOUNDARY ELEMENTS: Theory and Applications, Elsevier.