Title page for ETD etd-08252008-161944
|Type of Document
||Hyman, Mark C.
||The simulation of surface ship micro-bubble wakes
|Schetz, Joseph A.
|Hallauer, William L. Jr.
|Jakubowski, Antoni K.
|Liapis, Stergios I.
|Date of Defense
A method in which the transport and evolution of the bubble population in a surface ship
wake is numerically simulated is presented. The simulation is accomplished by
constructing an advective-diffusive transport model for the scalar bubble field and
solving this model for late times after ship passage. The bubble population model
requires convection velocities and turbulent diffusion information that is supplied by
solving the Reynolds-averaged parabolized Navier-Stokes equations with a Κ - ε
turbulence model. The mean flow equations are solved by approximating the differential
equations with a second order accurate finite difference scheme. The resulting large,
sparse, banded matrix is solved by applying a version of the conjugate gradient method.
The method has proven to be efficient and robust for the free shear flow problems of
interest here. The simulation is initiated with given information in a plane at some point
downstream of the ship from which the solution is propagated. The model is executed
for a single and a twin propeller ship at 15 knots. The simulation shows that the
development of the hydrodynamic and bubble near wake is dominated by ship geometry
via strong advective transport. The far wake is dominated by diffusion and bubble rise
and dissolution. Thus relatively large changes in geometry have a limited influence on
the far wake.
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