Experiments on a square section cylinder fixed and forced to oscillate transversely in a uni- form stream were conducted in a water tank.The Reynolds numberof the experiments is in the range of 3·10~3 tO 10~4,the...Experiments on a square section cylinder fixed and forced to oscillate transversely in a uni- form stream were conducted in a water tank.The Reynolds numberof the experiments is in the range of 3·10~3 tO 10~4,the amplitude to side length ratio A/D is up to 0.7 and the range of reduced velocity is 4.5<Vr<12.This study aims at investigating the lock-in phenomenon,the fluctuating lift and the phase shift between fluctuating lift and displacement of the oscillating cylinder.The problems on the aeroelastic insta. bility relating to present experimental results have been discussed.The flow visualization clearly shows that there are drastic changes of vortex-shedding from cylinder at the resonance point and the upper end of the lock-in range.The results of the flow visualization give better understanding of the physical mechanism of the phase shift.展开更多
We discuss the transport of an underdamped particle driven by an external fluctuation force in a spatially periodic asymmetric potential with correlated noises. The corresponding mathematical model is established. The...We discuss the transport of an underdamped particle driven by an external fluctuation force in a spatially periodic asymmetric potential with correlated noises. The corresponding mathematical model is established. The movement of the steady current of an underdamped particle is presented by the method of the numerical simulation. It is indicated that the value of the current may be negative, zero, or positive. The external fluctuation force and correlated noises can effect the current direction. Under the appropriate parameters, the correlated noises intensity may even raise a reversal of the current. Besides, we have noticed a phenomenon that particles with different weight have different directions during movement by the impact of the correlated noises and external fluctuation force. Therefore, the Brownian particles can be effectively separated according to their masses.展开更多
基金Project supported by National Natural Science Foundation of China
文摘Experiments on a square section cylinder fixed and forced to oscillate transversely in a uni- form stream were conducted in a water tank.The Reynolds numberof the experiments is in the range of 3·10~3 tO 10~4,the amplitude to side length ratio A/D is up to 0.7 and the range of reduced velocity is 4.5<Vr<12.This study aims at investigating the lock-in phenomenon,the fluctuating lift and the phase shift between fluctuating lift and displacement of the oscillating cylinder.The problems on the aeroelastic insta. bility relating to present experimental results have been discussed.The flow visualization clearly shows that there are drastic changes of vortex-shedding from cylinder at the resonance point and the upper end of the lock-in range.The results of the flow visualization give better understanding of the physical mechanism of the phase shift.
基金Projected supported by the National Natural Science Foundation of China(Grant No.11202120)the Fundamental Research Funds for the Central Universities of China(Grant Nos.GK201502007 and GK201701001)
文摘We discuss the transport of an underdamped particle driven by an external fluctuation force in a spatially periodic asymmetric potential with correlated noises. The corresponding mathematical model is established. The movement of the steady current of an underdamped particle is presented by the method of the numerical simulation. It is indicated that the value of the current may be negative, zero, or positive. The external fluctuation force and correlated noises can effect the current direction. Under the appropriate parameters, the correlated noises intensity may even raise a reversal of the current. Besides, we have noticed a phenomenon that particles with different weight have different directions during movement by the impact of the correlated noises and external fluctuation force. Therefore, the Brownian particles can be effectively separated according to their masses.
