Numerical Simulation of Bubble Distribution Characters in Ship′s Far Field Wakes

The mathematics model,which can calculate bubble number density distribution in ship′s far field wakes in the thermal stratified ocean environment is established for understanding the bubble distribution characters in ship wakes and providing the basis of detecting ship wakes.The model is made of parabolic Reynolds-averaged Navier-Stokes equations (PRaNS) and bubble transport equation in which the well known k-emodel is used.The characteristics of bubble number density distribution in ship wakes,the spread law of the bubble wakes width and the attenuation law of bubble number density are calculated usingthe model.The calculation results are compared with the measuring results of ship wakes,they agree well with each other qualitatively.The numerical simulation results show the bubbles which radius being 10~30 microns exist the most long time in the wakes.The detected object should be focused on the bubbles which radius being 10~30 microns for detecting the ship bubble wakes from the ship′s stern 5 kilometers at least,and the precision of detection should reach the level which can distinguish the 3% bubble number density at initial plane.