Journal of the Society of Naval Architects of Korea (대한조선학회논문집)

The Society of Naval Architects of Korea (대한조선학회)
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Simulation of Pressure Oscillation in Water Caused by the Compressibility of Entrapped Air in Dam Break Flow

댐 붕괴 유동에서 갇힌 공기의 압축성에 의한 물의 압력 진동 모사

  • Shin, Sangmook (Department of Naval Architecture and Marine Systems Engineering, Pukyong National University)
  • 신상묵 (부경대학교 조선해양시스템공학과)
  • Received : 2017.09.01
  • Accepted : 2017.12.11
  • Published : 2018.02.20
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Abstract

Pressure oscillation caused by the compressibility of entrapped air in dam break flow is analyzed using an open source code, which is a two-phase compressible code for non-isothermal immiscible fluids. Since compressible flows are computed based on a pressure-based method, the code can handle the equation of state of barotropic fluid, which is virtually incompressible. The computed time variation of pressure is compared with other experimental and computational results. The present result shows good agreements with other results until the air is entrapped. As the entrapped air bubbles pulsate, pressure oscillations are predicted and the pressure oscillations damp out quickly. Although the compressibility parameter of water has been varied for a wide range, it has no effects on the computed results, because the present equation of state for water is so close to that of incompressible fluid. Grid independency test for computed time variation of pressure shows that all results predict similar period of pressure oscillation and quick damping out of the oscillation, even though the amplitude of pressure oscillation is sensitive to the velocity field at the moment of the entrapping. It is observed that as pressure inside the entrapped air changes quickly, the pressure field in the neighboring water adjusts instantly, because the sound of speed is much higher in water. It is confirmed that the period of pressure oscillation is dominated by the added mass of neighboring water. It is found that the temperature oscillation of the entrapped air is critical to the quick damping out of the oscillations, due to the fact that the time averaged temperature inside the entrapped air is higher than that of surrounding water, which is almost constant.

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References

  1. Abrahamsen, B.C. & Faltinsen, O.M., 2011. The effect of air leakage and heat exchange on the decay of entrapped air pocket slamming oscillations. Physics of Fluids, 23(10), pp.102107. https://doi.org/10.1063/1.3638612
  2. Abrahamsen, B.C. & Faltinsen, O.M., 2012. The natural frequency of the pressure oscillations inside a water-wave entrapped air pocket on a rigid wall. Journal of Fluids and Structures, 35, pp.200-212. https://doi.org/10.1016/j.jfluidstructs.2012.07.004
  3. Chen, Z.J. & Przekwas, A.J., 2010. A coupled pressure-based computational method for incompressible/compressible flows. Journal of Computational Physics, 229, pp.9150-9165. https://doi.org/10.1016/j.jcp.2010.08.029
  4. Hu, C. & Kashiwagi, M., 2004. A CIP-based method for numerical simulations of violent free-surface flows. Journal of Marine Science and Technology, 9, pp.143-157. https://doi.org/10.1007/s00773-004-0180-z
  5. Hu, X.Y. Adams, N.A. & Iaccarino, G., 2009. On the HLLC Riemann solver for interface interaction in compressible multi-fluid flow. Journal of Computational Physics, 228, pp.6572-6589. https://doi.org/10.1016/j.jcp.2009.06.002
  6. Luo, M. Koh, C.G. Bai, W. & Gao, M., 2016. A particle method for two-phase flows with compressible air pocket. International Journal for Numerical Methods in Engineering, 108, pp.695-721. https://doi.org/10.1002/nme.5230
  7. Ma, Z.H. Causon, D.M. Qian, L. Mingham, C.G. & Ferrer, P.M., 2016. Numerical investigation of air enclosed wave impacts in a depressurised tank. Ocean Engineering, 123, pp.15-27. https://doi.org/10.1016/j.oceaneng.2016.06.044
  8. Ma, Z.H. Causon, D.M. Qian, L. Mingham, G. Gu, H.B. & Ferrer, P.M., 2014. A compressible multiphase flow model for violent aerated wave impact problems. Proceedings of The Royal Society A, 470, 20140542.
  9. Malgarinos, I. Nikolopoulos, N. & Gavaises, M., 2015. Coupling a local adaptive grid refinement technique with an interface sharpening scheme for the simulation of two-phase flow and free-surface flows using VOF methodology. Journal of Computational Physics, 300, pp.732-753. https://doi.org/10.1016/j.jcp.2015.08.004
  10. Mokrani, C. & Abadie, S., 2016. Conditions for peak pressure stability in VOF simulations of dam break flow impact. Journal of Fluids and Structures, 62, pp.86-103. https://doi.org/10.1016/j.jfluidstructs.2015.12.007
  11. Nielsen, K., 2003. Numerical prediction of green water loads on ships. Technical University of Denmark: Lyngby, Denmark.
  12. Park, C.W. & Lee, S., 2008. The effect of water compressibility on a rigid body movement in a water-filled duct driven by compressed air. Journal of the Society of Naval Architects of Korea, 45(4), pp.345-352. https://doi.org/10.3744/SNAK.2008.45.4.345
  13. Park, J.S. Kim, H.Y. Lee, K.H. Kwon, S.H. Jeon, S.S. & Jung, B.H., 2009. An experimental study on compressibility effect in sloshing phenomenon. Journal of Ocean Engineering and Technology, 23(4), pp.12-18.
  14. Phi, T.H. & Ahn, H.T., 2011. Air compressibility effect in CFD-based water impact analysis. Journal of the Society of Naval Architects of Korea, 48(6), pp.581-591. https://doi.org/10.3744/SNAK.2011.48.6.581
  15. Shin, S. Kim, I.C. & Kim, Y.J., 2005. Compressible two-phase flow computations using one-dimensional ALE Godunov method. Journal of the Society of Naval Architects of Korea, 42(4), pp.330-340. https://doi.org/10.3744/SNAK.2005.42.4.330
  16. Shin, S. Kim, I.C. & Kim, Y.J., 2006. Numerical analysis on spherically symmetric underwater explosion using the ALE Godunov scheme for two-phase flow. Journal of Computational Fluids Engineering, 11(1), pp.29-35.
  17. Zhou, Z.Q. Kat, J.O. & Buchner, B., 1999. A nonlinear 3D approach to simulate green water dynamics on deck. 7th International Conference on Numerical Ship Hydrodynamics, Nantes, France, 19-22 July 1999.