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Numerical Investigation of the Free Surface Effect On Underwater Vehicles

Sadat Jebreil, Maryam | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46291 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Sayyaadi, Hassan; Mehdigholi, Hamid
  7. Abstract:
  8. For observing the beauties of the sea, underwater vehicles are of the most appropriate equipment. In an optimized design of a vehicle, one should consider all applied forces and moments at all positions of the vehicle. Moving near the free surface is one of the positions of underwater vehicles. So, study on flow around a body moving near free surface is the subject of extensive research in marine hydrodynamic.
    The aim of the current investigation is a scrutiny of the influence of free surface effect on the flow around underwater vehicles. For this purpose, finite volume method is used to simulate flow around an axisymmetric body near free surface. In this simulation, volume of fluid (VOF) method is used for display free surface and its effect; and Reynolds averaged Navier-stokes(RANS) solver is used for modeling turbulence of the flow. The flow considered real, two dimensional, two phases and transient.
    Drag coefficients of forward speed are calculated at the speeds of 0.5, 1.5, 2.5m/s and at the depths of 1, 3, 5, 7 and 10 times of the maximum diameter of the vehicle. This study shows that, the ineffective depth changes for different speeds. Also, it is observed, the wave generation due to the presence of a body moving near free surface depends on two parameters: immersion depth of movable body and its forward speed, it means it depends on Froude number.
  9. Keywords:
  10. Drag Coefficient ; Two Phase Flow ; Computational Fluid Dynamics (CFD) ; Free Surfac Simulation ; Underwater Vehicle ; Finite Depth

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