Mass Transfer - Bush

Japanese: 物質移動 - ブッシツイドウ

The phenomenon in which a substance moves through a solid or fluid primarily by the action of diffusion. Movement in a solid is primarily caused by molecular diffusion due to differences in molecular concentration and thermal motion, while movement in a fluid is caused not only by molecular diffusion but also by turbulent diffusion due to irregular fluctuating motion caused by turbulence. However, even in the case of a fluid, near the interface with a solid, turbulence is suppressed and molecular diffusion becomes dominant. When it comes to mass transfer, the phenomenon of transfer between different phases, such as solid-liquid or gas-liquid, is more important than movement within such a homogeneous phase, and this is where the greatest interest lies.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

固体中あるいは流体中を物質が主として拡散の作用によって移動する現象。固体中の移動は，もっぱら分子の濃度差と熱運動による分子拡散で行われるが，流体中の移動には分子拡散のほか，乱流に起因する不規則な変動運動による乱流拡散が寄与する。ただし流体の場合でも固体との界面近くでは，乱れが抑制されるため分子拡散が支配的となる。物質移動という場合，このような均一相内の移動よりも，固体‐液体，気体‐液体のような異相間移動現象がより重要で，ここに大きな関心がもたれている。

出典　株式会社平凡社世界大百科事典第２版について　情報

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