Gas flow in nanoscale space has distinct characteristics compared with that in conventional macro-scale, due to the influence of space dimension on gas mean free path.

纳米尺度下的气体流动具有不同于常规尺度的规律，其中重要的特征是纳米间隙中气体分子自由输运行程将减小，进而影响气体的输运规律。

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The mean geometric free path or the characteristic dimension of a container is the important physical magnitude in describing the heat motion of gas molecules under low pressure.

几何平均自由程或容器的特征尺度是低压下描述气体分子热运动的重要物理量。

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