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单词 Fick law
释义

Fick law

中文百科

菲克定律 Fick's laws of diffusion

(重定向自Fick law)
图为宏观及微观观点下的分子扩散。一开始时,屏障(紫色线)的左边有一些溶质分子,而右边则没有。屏障被移走后,溶质开始扩散并愈来愈均匀地布满整个容器。上:一粒子在随机运动。中:更多粒子在随机运动,这个时候更容易看到溶质的分布是愈来愈均匀。下:当有大量溶质粒子的时候,所有随机性都消失了:溶质看起来就像有系统地且顺畅地,从高浓度的区域流到低浓度的区域去。菲克定律所描述的就是这种顺畅的流动。

菲克定律描述扩散作用,可以使用这条定律来求得扩散系数,D。定律由阿道夫·菲克于1855年推导出来。

假设从高浓度区域往低浓度流的通量大小与浓度梯度(空间导数)成正比,通过这个假设,菲克第一定律把扩散通量与浓度联系起来。在一维空间下的菲克定律如下:

其中

根据斯托克斯-爱因斯坦关系,\, D的大小取决于温度、流体黏度与分子大小,并与扩散分子流动的平均速度平方成正比。在稀的水溶液中,大部分离子的扩散系数都相近,在室温下其数值大概在0.6×10至2×10 m/s。而生物分子的扩散系数一般介于10及10 m/s之间。

英语百科

Fick's laws of diffusion 菲克定律

(重定向自Fick law)
Molecular diffusion from a microscopic and macroscopic point of view. Initially, there are solute molecules on the left side of a barrier (purple line) and none on the right. The barrier is removed, and the solute diffuses to fill the whole container. Top: A single molecule moves around randomly. Middle: With more molecules, there is a clear trend where the solute fills the container more and more uniformly. Bottom: With an enormous number of solute molecules, randomness becomes undetectable: The solute appears to move smoothly and systematically from high-concentration areas to low-concentration areas. This smooth flow is described by Fick's laws.

Fick's laws of diffusion describe diffusion and were derived by Adolf Fick in 1855. They can be used to solve for the diffusion coefficient, D. Fick's first law can be used to derive his second law which in turn is identical to the diffusion equation.

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更新时间:2025/6/18 19:17:26