Porous Jump Boundary Conditions
Porous jump conditions are used to model a thin "membrane'' that has known velocity (pressure-drop) characteristics. It is essentially a 1D simplification of the porous media model available for cell zones. Examples of uses for the porous jump condition include modeling pressure drops through screens and filters, and modeling radiators when you are not concerned with heat transfer. This simpler model should be used whenever possible (instead of the full porous media model) because it is more robust and yields better convergence.
The thin porous medium has a finite thickness over which the pressure change is defined as a combination of Darcy's Law and an additional inertial loss term:
(7.22-1)
where
is the laminar fluid viscosity,
is the permeability of the medium,
is the pressure-jump coefficient,
is the velocity normal to the porous face, and
is the thickness of the medium. Appropriate values for
and
can be calculated using the techniques described in Section 7.19.6.
User Inputs for the Porous Jump Model
Once the porous jump zone has been identified (in the Boundary Conditions panel), you will set all modeling inputs for the porous jump in the Porous Jump panel(Figure 7.22.1), which is opened from the Boundary Conditions panel (as described in Section 7.1.4).
Figure 7.22.1:ThePorous JumpPanel
The inputs required for the porous jump model are as follows:
1. Identify the porous-jump zone.
2. Set the Face Permeability of the medium (
in Equation 7.22-1).
3. Set the Porous Medium Thickness (
).
4. Set the Pressure-Jump Coefficient (
).
5. Define the discrete phase boundary condition for the porous jump (for discrete phase calculations).
Identifying the Porous Jump Zone
Since the porous jump model is a 1D simplification of the porous media model, the porous-jump zone must be modeled as the interface between cells, rather than a cell zone. Thus the porous-jump zone is a type of internal face zone (where the faces are line segments in 2D or triangles/quadrilaterals in 3D). If the porous-jump zone is not identified as such by default when you read in the grid (i.e., if it is identified as another type of internal face zone), you can use the Boundary Conditions panel to change the appropriate face zone to a porous-jump zone.
Define
Boundary Conditions...
The procedure for changing a zone's type is described in Section 7.1.3. Once the zone has been changed to a porous jump, you can open the Porous Jump panel (as described in Section 7.1.4) and specify the porous jump parameters listed above.
Defining Discrete Phase Boundary Conditions for the Porous Jump
If you are modeling a discrete phase of particles, you can set the fate of particle trajectories at the porous jump. See Section 22.13 for details.
Postprocessing for the Porous Jump
Postprocessing suggestions for a problem that includes a porous jump are the same as for porous media problems. See Section 7.19.9.
本文档为【多孔跳跃边界条件】，请使用软件OFFICE或WPS软件打开。作品中的文字与图均可以修改和编辑，
图片更改请在作品中右键图片并更换，文字修改请直接点击文字进行修改，也可以新增和删除文档中的内容。
该文档来自用户分享，如有侵权行为请发邮件ishare@vip.sina.com联系网站客服，我们会及时删除。
[版权声明] 本站所有资料为用户分享产生，若发现您的权利被侵害，请联系客服邮件isharekefu@iask.cn，我们尽快处理。
本作品所展示的图片、画像、字体、音乐的版权可能需版权方额外授权，请谨慎使用。
网站提供的党政主题相关内容(国旗、国徽、党徽..)目的在于配合国家政策宣传，仅限个人学习分享使用，禁止用于任何广告和商用目的。
浙公网安备 33021202002483