抄録
In larviculture, it is known that mass mortality occurs during larval and juvenile stages. The survival
rate of larval fishes is considered to be sensitive to the flow structure in rearing tanks, which is
constructed with aeration. In order to reduce the early mortality during the early phase of larviculture, it
is necessary to control/understand flow field in rearing tanks. Previously, Shiotani et al. （2005）
investigated the flow field in a circular rearing tank by a two dimensional single-phase simulation.
However, the simulation results did not agree well with flow visualization results. Then, Sumida et al.
（2013） carried out two dimensional two-phase flow simulations for circular rearing tanks, which showed
good agreement with the flow visualization results. However, information on the flow field in rectangular
tanks is scarce. Therefore, we investigated flow patterns in rectangular tanks by three dimensional twophase
bubbly flow simulations. The rectangular tanks with three different aspect ratios AR （ratio of
height to half-width of tank） are analyzed in this research. Symmetrical vortex structures are observed
at right and left of the tanks at a vertical cross-section in all AR cases. Characteristics of three
dimensional flows in the rectangular tanks are clarified in this research which will be beneficial for
larviculture.
