请教多孔介质porosity&void fraction 定义辨析

rock218

在帮助文档中介绍多孔介质的时候，有两个定义不能完全明白：a is the porosity of the media defined as the ration of the volume occupied by the fluid to the totail volume;  b is the void fraction defined as the volume of voids divided by the volume of the packed bed region.  我觉得a 也就是 porosity 翻译成孔隙度比较好，那void fraction 翻译成什么呢，它们的实质是不是一样的？

xiaofish

a porosity should be a genenral definition
b void fraction is usually used for packed(fixed) bed.packed beds are constituted by many particles. if the particles are regarded as solid, then the two definitions are the same. if the particles have porous structure, then the two definitions are not the same.
my own opion. hehe  

zwzsh

请问多孔介质流动计算，你们是用何软件计算，能否介绍一下