Numerical simulation of two self propelled fish swimming in a side by side arrangement
Numerical simulations of two self propelled fish in a side by side arrangement has been numerically investigated using an adaptive version of immersed boundary method.Two typical cases of the phase difference between the adjacent fish,i.e.,in phase and anti phase self propelled swimming,are considered.Compared with the performance of a single self propelled fish swimming,the results show that:(1)the swimming speed of fish school is smaller than that of an individual fish,and decrease as the lateral distance decrease,and that of the anti phase case is bigger than that of the in phase case with the same lateral distance;(2)the drag of fish school is bigger than that of an individual fish,and increases as the lateral distance decreases;(3)the power consumption of the anti phase case increases as the lateral distance decreases,which is opposite to that of the in phase case;(4)the propulsive efficiency increases slightly when the lateral distance is bigger than 0.5L(Lis the fish body length).Therefore,with the consideration of the swimming speed and the propulsive efficiency,two side by side arranged fish should beat their tails in anti phase and the lateral distance should be bigger than 0.5L,which is consistent with the observations in nature.