International Journal Of Coastal, Offshore And Environmental Engineering(ijcoe)

International Journal Of Coastal, Offshore And Environmental Engineering(ijcoe)

Numerical Study on Hydrodynamic Force and Wave Induced Vortex Dynamics around Cylindrical Pile

Authors
Mohammad Mohammad Beigi Kasvaei 1
Mohammad Hossein Kazeminezhad 1
Abbas Yeganeh-Bakhtiary 2
1 Iranian National Institute for Oceanography & Atmospheric Science, Tehran, Iran
2 School of Civil Engineering, IUST, Tehran, Iran
10.29252/ijcoe.1.4.1
Abstract
Three-dimensional numerical simulation of regular waves passing over cylindrical monopile has been conducted to investigate the hydrodynamic force and vortex dynamics. To do so, the rectangular wave flume and monopile is modeled on a solver; available in the open-source CFD toolkit OpenFOAM®. The solver applied RANS equations with VOF method for tracking free surface. Model validation has been done by comparison numerical results with the experimental ones and admissible agreement has been seen. Computations have been done for four cases with different wave characteristics consequently for different Keulegan-Carpenter numbers (KC). Hydrodynamic in-line force acting upon pile was studied and the results indicated that the total in-line force increases as KC number increases. In addition, when vortex shedding develops, drag force component increases and inertia force component decreases. The vortex dynamics around the pile was investigated by means of Q criterion and vorticity field. It was seen that by increasing KC number larger than 6, vortex shedding will be happened. Moreover, variation of bed shear stress around the pile has been investigated and it was seen that the bed shear stress is influenced by KC number which is result of existence of horseshoe vortices. The bed shear stress near the pile is negative due to existing of the horseshoe vortex. It begins when KC exceeds 6 and by increasing KC up to 20, the magnitude of negative values of bed shear stress near the pile increased which implies horse shoe vortices are completely formed. This also complies the experimental results.
Keywords
Keulegan-Carpenter
OpenFOAM
RANS Equations
Vortex Shedding
Wave-Pile Interaction
  1. Sumer, B. M., Christiansen, N., & Fredsøe, J. (1997). The horseshoe vortex and vortex shedding around a vertical wall-mounted cylinder exposed to waves. Journal of Fluid Mechanics, 332, 41-70. [DOI:10.1017/S0022112096003898]
  2. Morgan, G. C. J., Zang, J., Greaves, D., Heath, A., Whitlow, C., & Young, J. (2011). Using the rasInterFoam CFD model for wave transformation and coastal modelling. Coastal Engineering Proceedings, 1(32), 23. [DOI:10.9753/icce.v32.waves.23]
  3. Amini Afshar, M. (2010). Numerical wave generation in Open FOAM®.
  4. Baykal, C., Sumer, B. M., Fuhrman, D. R., Jacobsen, N. G., & Fredsøe, J. (2015). Numerical investigation of flow and scour around a vertical circular cylinder. Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 373(2033), 20140104. [DOI:10.1098/rsta.2014.0104]
  5. Mo, W., Irschik, K., Oumeraci, H., & Liu, P. L. F. (2007). A 3D numerical model for computing non-breaking wave forces on slender piles. Journal of Engineering Mathematics, 58(1), 19-30. [DOI:10.1007/s10665-006-9094-6]
  6. Jacobsen, N. G., Fuhrman, D. R., & Fredsøe, J. (2012). A wave generation toolbox for the open‐source CFD library: OpenFoam®. International Journal for Numerical Methods in Fluids, 70(9), 1073-1088. [DOI:10.1002/fld.2726]
  7. Benitz, M. A., Schmidt, D. P., Lackner, M. A., Stewart, G. M., Jonkman, J., & Robertson, A. (2014, June). Comparison of hydrodynamic load predictions between reduced order engineering models and computational fluid dynamics for the oc4-deepcwind semi-submersible. In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering (pp. V09BT09A006-V09BT09A006). American Society of Mechanical Engineers. [DOI:10.1115/OMAE2014-23985]
  8. Higuera, P., Lara, J. L., & Losada, I. J. (2013). Simulating coastal engineering processes with OpenFOAM®. Coastal Engineering, 71, 119-134. [DOI:10.1016/j.coastaleng.2012.06.002]
  9. Paulsen, B. T., Bredmose, H., & Bingham, H. B. (2014). An efficient domain decomposition strategy for wave loads on surface piercing circular cylinders. Coastal Engineering, 86, 57-76. [DOI:10.1016/j.coastaleng.2014.01.006]
  10. Stahlmann, A. (2013, June). Numerical and experimental modeling of scour at foundation structures for offshore wind turbines. In The Twenty-third International Offshore and Polar Engineering Conference. International Society of Offshore and Polar Engineers.
  11. Paulsen, B. T., Bredmose, H., Bingham, H. B., & Jacobsen, N. G. (2014). Forcing of a bottom-mounted circular cylinder by steep regular water waves at finite depth. Journal of fluid mechanics, 755, 1-34. [DOI:10.1017/jfm.2014.386]
  12. Jiang, C., Yao, Y., Deng, Y., & Deng, B. (2015). Numerical Investigation of Solitary Wave Interaction with a Row of Vertical Slotted Piles. Journal of Coastal Research, 31(6), 1502-1511. [DOI:10.2112/JCOASTRES-D-14-00210.1]
  13. Haddorp, R. (2005). Predictability of Scour at Large Piles due to Waves and Currents.
  14. Sumer, B. M. (2002). The mechanics of scour in the marine environment (Vol. 17). World Scientific Publishing Company. [DOI:10.1142/4942]
  15. Hoffmans, G.J.C.M., Verheij, H.J. (1997): "Scour Manual", Rotterdam.
  16. Coastal Engineering Manual (2003): "EM 1110-2-1100 (Part VI) ", Chapter 5, p.242-245, Washington.
  17. Isaacson, M. (1979). Wave-induced forces in the diffraction regime. Mechanics of wave-induced forces on cylinders.
  18. Menter, F. R. (1994). Two-equation eddy-viscosity turbulence models for engineering applications. AIAA journal, 32(8), 1598-1605. [DOI:10.2514/3.12149]
  19. WILCOX, D. (1988). Reassessment of the scale-determining equation for advanced turbulence models. AIAA journal, 26(11), 1299-1310. [DOI:10.2514/3.10041]
  20. Hirt, C. W., & Nichols, B. D. (1981). Volume of fluid (VOF) method for the dynamics of free boundaries. Journal of computational physics, 39(1), 201-225. [DOI:10.1016/0021-9991(81)90145-5]
  21. Jacobsen, N. G. (2017). waves2Foam Manual.
  22. OS, D. (2011). J101, Design of Offshore Wind Turbine Structures. DET NORSKE VERITAS AS, Ausgabe, 9.
  23. Chen, Q., Zhong, Q., Qi, M., & Wang, X. (2015). Comparison of vortex identification criteria for planar velocity fields in wall turbulence. Physics of Fluids, 27(8), 085101. [DOI:10.1063/1.4927647]
  24. Sumer, B. M. (2006). Hydrodynamics around cylindrical structures (Vol. 26). World scientific. [DOI:10.1142/6248]