Eckart stable gyration of one ball and two balls rotating in opposite directions was realized in an ultrasonic fountain. It is found that the gyration of the balls accelerates as the ultrasonic power increases.

• Eckart的声流理论,实现了超声喷泉中一个球体的旋转和两个球体按相反方向的旋转,同时观察到这些球体的旋转随超声功率的增大而加速。