倾斜波动壁面上液膜表面波演化特性的影响

Influence of the inclined waving wall on the surface wave evolution of liquid film

对倾斜波动壁面上流体表面波的演化规律进行了研究.考虑壁面形状为正弦波动壁面的情况,分析液膜流动的线性稳定性,并研究不同倾斜角度下扰动波波形随时间的演化情况及流经不同壁面形状时扰动波的波形变化.对整体的波形结构分析可知,随着时间的演化,扰动波的演化过程呈现为更大波长的近周期变化规律,与平板上的流动结构对比发现波动情况变得更加复杂;当液膜流经波动壁面时,扰动波在空间上不再呈现规律性变化,且随着壁面倾斜角度的增加,扰动波的振幅逐渐增加;在相同的壁面倾角下,波动壁面上的扰动波振幅大于平板壁面的扰动情况,且波形扭曲程度更明显;随着Re的增加,扰动波振幅逐渐增加,其对应波形的扭曲程度加深,且随着壁面振幅的增加,静态波振幅及扰动波振幅均随之增加,对应的行进波周期不变.最后,分析了壁面倾斜角度对流动稳定性的影响.

In this paper, the evolution of the fluid surface wave on an inclined waving wall is investigated. The waving wall is assumed to have a sinusoidal fluctuating surface, and the linear stability of the liquid film flow is analyzed. In addition,the evolutions of the disturbance wave under different tilt angles, and the variations in this wave when passing through different wall shapes are studied. It can be observed that the time evolution of the disturbance wave appears to be a near periodic variation of a larger wavelength. Further, by comparing its flow structure with that for the flat plate wall, it is found that the wave conditions are more complex. When the fluid flows through the waving wall, the disturbance wave no longer displays a regular change in space, and its amplitude increases with the tilt angle of the wall increasing. For the same tilt angle, the amplitude of the disturbance wave in the waving wall is greater than that for the flat plate wall,and the distortions in waveform are more obvious. As Re increases, the amplitude of the disturbance wave increases gradually, and the distortion of the corresponding wave increases as well. Further, with the increase of wall surface amplitude, the amplitudes of the static and disturbance waves increase, whereas the corresponding traveling-wave period remains unchanged. Finally, the influence of the wall tilt angle on flow stability is analyzed.