多孔介质的方向

nlhy123

哪位高手能用语言描述一下，多孔介质的方向是什么的方向啊？

xrs333

各向异性多孔介质用的。各向同性用不到。

seaharrier

多孔介质材料本身一般都是各向做成不同的，
比如说某个方向透气性透水性好，垂直这个方向就很难透过。

nlhy123

高手，我再追问下。上边这个方向是描述的透气透水好的方向吗？

xrs333

那两个direction vector称为第一主方向和第二主方向，方向随你怎么定义，第三个主方向与这两个正交。关键是损失系数的方向要与他们对应。

nlhy123

与direction vector对应的意思是不是说在透气好的地方损失小，阻力系数小？那沿着direction vector的方向一定是阻力系数小吗？

xrs333

先定义方向，再定义各方向的阻力系数。

mayo_0

7.19.6 User Inputs for Porous Media

In 3D there are three possible categories of coefficients, and in 2D there are two:

    In the isotropic case, the resistance coefficients in all directions are the same (e.g., a sponge). For an isotropic case, you must explicitly set the resistance coefficients in each direction to the same value.

    When (in 3D) the coefficients in two directions are the same and those in the third direction are different or (in 2D) the coefficients in the two directions are different, you must be careful to specify the coefficients properly for each direction. For example, if you had a porous region consisting of cylindrical straws with small holes in them positioned parallel to the flow direction, the flow would pass easily through the straws, but the flow in the other two directions (through the small holes) would be very little. If you had a plane of flat plates perpendicular to the flow direction, the flow would not pass through them at all; it would instead move in the other two directions.

    In 3D the third possible case is one in which all three coefficients are different. For example, if the porous region consisted of a plane of irregularly-spaced objects (e.g., pins), the movement of flow between the blockages would be different in each direction. You would therefore need to specify different coefficients in each direction.

nlhy123

大师，你有中文版的吗？