表明壁面的“阻尼”影响主要集中在近壁面0 . 5 D以内，在径向上流动既有顺压梯度，又有逆压梯度。

It is shown that the "damping" effect mainly exists in the zone of 0.5d from the impingement wall, and there are positive as well as adverse pressure gradient in the radial direction.

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数值计算结果表明，顺压梯度有明显的延缓转捩作用，逆压梯度有较强的不稳定作用。

The numerical calculation results show that the favorable pressure gradients have apparent laminar flow control property, and the unfavorable pressure gradients have a strong unstable influence.

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They move from regions of high concentration to regions of low concentration by this natural flow down a concentration gradient.

从高浓度区域,向低浓度区域流动,顺浓度梯度流动

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Movement down a concentration gradient occurs fairly rapidly over short distances like a micron or so, like the size of a bacterium.

顺浓度梯度扩散在一微米左右的短距离内,相当迅速,一微米相当于一个细菌的大小

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