[求助]第二相材料加不上了，哪位给指点一下

sunseahe

[这个贴子最后由sunseahe在 2008/04/17 07:15pm 第 1 次编辑]

我是做了一个两相流的 VOF模型，遇到第二相材料加不上的问题，我已经定义了solid材料coal，可是phase material列表只有air,请教下这是什么原因？

sunseahe

我找到答案了 ，回来汇报一下。
气固（小颗粒）两相流应该用欧拉-欧拉模型，通过定义fluid类型材料并将粘性设为很小的 值（接近0）来模拟固体颗粒，而不是定义solid类型材料。
原文地址：http://cache.baidu.com/c?m=9d78d513d99612ee4fece4690d60c0676915dd3d6781c7150e80cd15d6701c011969b9fd61600705a0d861365cf0191babb6217240597bf18cc8ff1d8bfc852858d97b292149dd5612a549f4975b639c62cb0bfeaf6eb6efab2592da8182990f0e9644040cddacd5015c438e34a75126e3a2cd1555184fadec4666f55e60299b651df41ca8f73318048be1dd580d857990270696d937a73e16f449f95a0c2532a2&p=8b2a944486cc46ac0abfd0364b4394&user=baidu
摘录如下：
question
Dear All,
I am simulating a gas-solid two phase flow in a vertical pipe using Euler-Euler approach rather than Euler-Lagrange method. When I select solid as the thermodynamic state in the material editor, I have to use Euler-Lagrange method. However, I have to select liquid as the thermodynamic state if I want to use Euler-Euler approach. It';s really a confusion since particles are solid. So, how to define solid phase in the materail editor?
Another problem is the boundary conditions. I noticed that in Tutorial 15 for air inlet, a velocity of 5m/s and zero volume fraction are used for water at air inlet. Why don';t use 0m/s and zero volume fraction for water since there is no water entering into the domain through air inlet?
Liwau

reply
Hi Liwau,
Both phases must be fluids (liquid or gas) for the Euler-Euler method. If you are modelling solid particles then your only option is the Lagrangian approach.
Glenn
reply
Actually......
Just "tell" the model that the dispersed phase is a liquid. Give the material the appropriate density and a viscosity of nearly zero (1.0E-10). This is counter intuitive, but ensures that there is no visous transport of momentum within the solid phase. Make sure that you use Shiller Naumann for sphere';s and set the disperse phase to laminar (otherwise your zero viscosity will be overridden by a turbulent viscosity).
Boundary conditions at inlets/outlets for phases which have zero volume fraction are best set to the continuous phase velocity. This ensures that the slip velocity between the phases is zero and the drag between phases will then be zero, even if numerical round-off gives you a trace component.
Jeff

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