Full Scale Simulations of the Bubbly Flow Around the Research Vessel Athena With Incoming Waves and Discretized Propeller

Simulations of the two-phase bubbly flow around the research vessel Athena are presented. These are performed using a polydisperse model where several bubbles sizes are modeled. Intergroup transfer mechanisms such as breakup, coalescence and dissolution of air into water are considered. These simulations are performed on the fully appended Athena R/V including the rotating propeller. In this way the interaction of the stream of bubbles pushed down by the ship and the propeller is explicitly taken into account. Incoming regular waves are included in the simulations to mimic the observations of available data that show a pulsating entrainment of bubbles due to the waves. The effect of the several intergroup transfer mechanisms on the bubbly field around the ship is analyzed and discussed in depth. Simulations are performed in full scale to predict realistic turbulent structures and allow for a valid comparison with experiments.

Social influences on intergroup transfer by pine voles (Microtus pinetorum)

Selection to obtain mating opportunities is hypothesized to be a major factor in dispersal. Thus, if individuals move to another group or switch nests to maximize their reproductive opportunities, they should move to groups or sites where they minimize competition for resources or mates and where they can find potential mates. We examined movement of pine voles (Microtus pinetorum) in an orchard habitat. Males dispersed later than females, but the two sexes showed similar patterns of movement with respect to conspecifics. Males and females immigrated to territories that contained some opposite-sex conspecifics; they also immigrated to territories without same-sex conspecifics. The latter suggests that they may avoid competitors and move to territories where an opening exists. When female breeders were removed from a social group, a replacement female arrived and began to breed relatively rapidly. In control groups where breeding females were not removed, no replacement females appeared. These results suggest that pine voles, at least females, may monitor vacancies and immigrate if a vacancy appears.