英文:
How to access gmsh code from python after importing mesh into Fipy?
问题
我已经生成了一个通过Gmsh2D导入到FiPy中的gmsh网格。我想要处理表面面以设置边界条件，但我不知道如何做。
在FiPy的文档中，我找到了一些示例，建议在导入网格后命名某些线条以后续引用。在我将网格导入到FiPy之后，我该如何做这个？
// 注意：如果您不使用任何标签，所有单元格都将包括在内。
Physical Surface("Outer") = {1};
Physical Surface("Middle") = {2};
Physical Surface("Inner") = {3};
// 对外部边界的“西北部分”进行标记
// 注意：您只需要为您感兴趣的边界标记Face元素
//（在2D中为Physical Line，在3D中为Physical Surface）。
// FiPy不需要它们来构建网格。
Physical Line("NW") = {5};
编辑：
对于简单的表面面，这将起作用：
我忽略了mesh.exteriorFaces。
对于一个简单的圆，这会导致简单的解决方案：
xfc, yfc = mesh.faceCenters() # 返回x面中心坐标，...
xcc, ycc = mesh.cellCenters()
plot(xfc[where(mesh.exteriorFaces == False)],yfc[where(mesh.exteriorFaces == False)],'ro', label='inside')
plot(xfc[where(mesh.exteriorFaces == True)],yfc[where(mesh.exteriorFaces == True)],'ko', label='surface')
legend()
尽管如此，我仍在寻找如何从外部访问gmsh代码的答案，但也许这会对其他人有所帮助:)
英文:
I have generated a gmsh mesh that I imported into FiPy via Gmsh2D. I would like to adress the surface Faces to set boundary conditions but I did not know how to.
In FiPy examples I found in the documentation it is suggested to name certain lines to address them later. How do I do this after I imported the mesh into fipy?
// note: if you do not use any labels, all Cells will be included.
Physical Surface("Outer") = {1};
Physical Surface("Middle") = {2};
Physical Surface("Inner") = {3};
// label the "north-west" part of the exterior boundary
// note: you only need to label the Face elements
// (Physical Line in 2D and Physical Surface in 3D) that correspond
// to boundaries you are interested in. FiPy does not need them to
// construct the Mesh.
Physical Line("NW") = {5};
-----------------
Edit:
For simple surface faces this will work:
I overlooked mesh.exteriorFaces.
For a simple circle this leads to the simple solution:
xfc, yfc = mesh.faceCenters() # returns x faceCenters coordinate, ...
xcc, ycc = mesh.cellCenters()
plot(xfc[where(mesh.exteriorFaces == False)],yfc[where(mesh.exteriorFaces == False)],'ro', label='inside')
plot(xfc[where(mesh.exteriorFaces == True)],yfc[where(mesh.exteriorFaces == True)],'ko', label='surface')
legend()
Nevertheless i am still searching for an answer on how to access the gmsh code from outside, but maybe this helps others:)
答案1
得分: 1
"Outer" 不是一个物理面，它是一组物理单元。要访问 "Outer" 的边界面，您可以将以下内容添加到您的 Gmsh 脚本中：
Physical Line("Outer Boundary") = {1, 2, 3, 4, 5, 6, 7, 8};
然后应用一个约束条件：
var.constrain(value, where=squaredCircle.physicalFaces["Outer Boundary"])
正如您发现的，您始终可以访问 mesh.exteriorFaces 以获取定义整个网格边界的面（即只有一侧有单元的面）。使用 Physical Surface 定义的 Gmsh 域不一定由 mesh.exteriorFaces 限定。
英文:
"Outer" is not a physical face, it is a set of physical cells. To access the bounding faces of "Outer", you can add
Physical Line("Outer Boundary") = {1, 2, 3, 4, 5, 6, 7, 8};
to your Gmsh script, and then apply a constraint with
var.constrain(value, where=squaredCircle.physicalFaces["Outer Boundary"])
As you found, you can always access mesh.exteriorFaces to get the faces that define the boundaries of the entire mesh (i.e., faces which only have a cell on one side). The Gmsh domains defined with Physical Surface are not necessarily bounded by mesh.exteriorFaces.
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