摄动的Poiseuille流的上游特征值的渐近分析

考虑的问题是二维粘性渠流．当雷诺数Ｒ→０和Ｒ→＋∞时，讨论了Ｐｏｉｓｅｕｉｌｌｅ流在定常的摄动下的上游特征值的渐近性质，结果表明，Ｗｉｌｓｏｎ（１９６９）对该问题的下游特征值的分析也适用于上游的分析，且上游特征值的渐近结果与已有的Ｂｒａｍｌｅｙ和Ｄｅｎｎｉｓ（１９８２）的数值结果是一致的．

Experimental Study of the Viscous Pump with a Helical Channel Rotor:Torsion Effect of the Channel

The viscous pump,which has a rotor with a helical square channel,is studied experimentally.The non-dimen-sional channel curvature is taken to be about 0.1.Three types of torsion of the channel are made to investigate the torsion effect on the flow characteristics.We measure the flux through the channel at a constant rotor speed by changing the pressures at the entrance and exit of the pump.We also observe the secondary flow at a cross-section of the channel.Some of the results obtained are shown as follows:The friction factor along the channel to get the same flux is large for large channel torsion at a constant rotation,and becomes small when the favorable rotation of the rotor to the flow is applied.As for the secondary flow in a cross-section,there appear several types of vortex.When there is no rotation,the secondary flow is almost a symmetric two-vortex type for small flux as is the ordinary Dean vortex,but it changes to a four-vortex type when the flux is large.The secondary flow becomes asymmetric as the rotation is applied.We have unsteady flow patterns at large flux and rotation.