The paper presents a study of the slip velocity for almost spherical bubbles in a downward laminar tube flow. The local slip velocity is defined as a difference between the mean liquid velocity (measured with electrodiffusional method) and the mean bubble velocity (measured with a modified LDA tool with a small size of measurement volume). The law for slip velocity for downward flow is significantly different from a similar law for upward flow. This reveals that the bubble flow motion is rather random than structured in the upward flow.

中文翻译：

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向下层流时的局部气泡滑移速度

本文介绍了层流向下流动中几乎球形气泡的滑动速度的研究。局部滑移速度定义为平均液体速度（用电扩散法测量）和平均气泡速度（用改良的LDA工具测量，测量体积小）之间的差。向下流动的滑移速度定律与向上流动的类似定律明显不同。这表明气泡流动运动是随机的，而不是向上流动的结构化。