The Modeling Of Air Entrainment Processes For Surface Ships.

Abstract

Direct numerical simulations (DNS) of air entrainment by breaking bow waves of
naval surface ships are outside of the computational reach of the most powerful computers in
the foreseeable future. This creates a need for models of air entrainment for applications in
numerical simulations for ship design. We present a model that is based on the local liquid velocity
and the distance to the interface, which determines whether air entrainment should occur.
Using this model and the bubble size distributions measured by Deane and Stokes1 we simulate
the air entrainment in the breaking bow wave experiments of Wanieski et al.2 Comparison
against these experimental data is good. We then apply this model to simulate the flow around
naval combatant DTMB5415. The model predicts air entrainment in all the regions where it
is actually observed at sea, namely the breaking bow wave, along the water/air/hull contact
line and around the transom stern. To the best of our knowledge this is the first model of air
entrainment that compares favorably with data at laboratory scale and presents the right trends
at full-scale conditions.