Question

我用Gmsh创建了一个网格（一个有孔的表面，然后将其拉伸）。现在我想用例如MatplotlibViewer（Mayavi在我的两台计算机上均无法运行）。我曾希望可以使用mesh.physicalFaces定义一个新的网络，但是如果可能的话，我还没有弄清楚。我的第二次尝试是使用Gmsh将网格再次应用到“拉伸”命令。但是网格不对应于3D版本。有人可以给我一个线索吗？也就像另一种表示方法一样。

我正在使用Win10，Fipy 3.1.3，Python 3.6

import numpy as np
from fipy import *
#%%
def func_mesh():
    mesh = Gmsh3D('''
    Geometry.OCCAutoFix = 0;
    SetFactory("OpenCASCADE");

    x = 1.;
    bseg = 0.08;
    bs= bseg*x;
    ls = 2.1; 
    cl = 0.01;
    radius = 0.006;

    // Exterior (bounding box) of mesh
    Point(1) = {0, 0, 0, cl};
    Point(2) = {0, bs, 0, cl};
    Point(4) = { bs,  0, 0, cl};
    Point(3) = {bs,  bs, 0, cl};
    Line(1) = {1, 2};
    Line(2) = {2, 3};
    Line(3) = {3, 4};
    Line(4) = {4, 1};
    Line Loop (21) = {1,2,3,4};


    //Circle
    Point(5) = {bseg/2 - radius, bseg/2, 0, cl};
    Point(6) = {bseg/2, bseg/2 + radius, 0, cl};
    Point(7) = { bseg/2 + radius, bseg/2, 0, cl};
    Point(8) = {bseg/2, bseg/2 - radius, 0, cl};
    Point(9) =  {bseg/2, bseg/2, 0, cl};

    Circle(10) = {5,9,6};
    Circle(11) = {6,9,7};
    Circle(12) = {7,9,8};
    Circle(13) = {8,9,5};
    Line Loop(22) = {10,11,12,13};
    Plane Surface(40) = {22}; //cycl

    Plane Surface(15) = {21, 22}; //Surface with a hole


    id[] = Extrude {0, 0, ls} {Surface{15}; Layers{210}; Recombine;};

    Surface Loop(2) = {46, 45, 48, 47, 49, 41, 44, 43, 42, 15};

    Physical Volume("Vol") = {id[]};

    Physical Surface("surf_ges") = {41, 42, 43, 44, 49, 47, 45, 48, 46, 15};

    Physical Surface("HX") = {45, 46, 48, 47};

    Physical Surface("Extr") = {15};

    ''')
    return mesh

    mesh = func_mesh()

    x,y,z = mesh.cellCenters 
    X,Y,Z = mesh.faceCenters

    tS = CellVariable(name="storage", 
                      mesh=mesh, 
                      value=367., 
                      hasOld=True)

submesh = mesh.physicalFaces['Extr']
xsub, ysub = submesh.cellCenters
tSslice = CellVariable(name = 'tSsclice',
                 mesh = submesh,
                 value = tS[z== z[0]])
viewer = MatplotlibViewer(vars = tSslice)

此尝试失败的错误消息是：AttributeError：'binOp'对象没有属性'cellCenters'。如果仅在拉伸命令之前重新定义网格，则会得到：由于tSslice的形状，导致出现“ ValueError：太多值无法解包（预期2）”。感谢您的帮助

Answer 1

submesh不是Mesh；这是一个遮罩，用于识别mesh的哪些面包含在表面Extr中。

FiPy无法从另一个网格中提取网格。使用Mesh2D掩码submesh和mesh.vertexCoords创建mesh.faceVertexIDs应该是可行的，但这并不简单。

从理论上讲，您可以调用Gmsh2D直到Plane Surface(15) = {21, 22}; //Surface with a hole的所有内容，但是我发现生成的元素数量与z == z[0]处的3D切片数量不同。

啊，我明白了。我以为Extrude操作导致了棱柱形单元，但事实并非如此。细胞是四面体的。由于mesh的像元并非都具有相同的四面体几何形状，因此不能保证所有以Extr为基础的像元都位于z == z[0]的中心。更好的方法是使用FiPy的CellVariable插值在tS的坐标处提取tSslice的值：

from fipy import *

geo = '''
Geometry.OCCAutoFix = 0;
SetFactory("OpenCASCADE");

x = 1.;
bseg = 0.08;
bs= bseg*x;
ls = 2.1; 
cl = 0.01;
radius = 0.006;

// Exterior (bounding box) of mesh
Point(1) = {0, 0, 0, cl};
Point(2) = {0, bs, 0, cl};
Point(4) = { bs,  0, 0, cl};
Point(3) = {bs,  bs, 0, cl};
Line(1) = {1, 2};
Line(2) = {2, 3};
Line(3) = {3, 4};
Line(4) = {4, 1};
Line Loop (21) = {1,2,3,4};


//Circle
Point(5) = {bseg/2 - radius, bseg/2, 0, cl};
Point(6) = {bseg/2, bseg/2 + radius, 0, cl};
Point(7) = { bseg/2 + radius, bseg/2, 0, cl};
Point(8) = {bseg/2, bseg/2 - radius, 0, cl};
Point(9) =  {bseg/2, bseg/2, 0, cl};

Circle(10) = {5,9,6};
Circle(11) = {6,9,7};
Circle(12) = {7,9,8};
Circle(13) = {8,9,5};
Line Loop(22) = {10,11,12,13};
Plane Surface(40) = {22}; //cycl

Plane Surface(15) = {21, 22}; //Surface with a hole


id[] = Extrude {0, 0, ls} {Surface{15}; Layers{210}; Recombine;};

Surface Loop(2) = {46, 45, 48, 47, 49, 41, 44, 43, 42, 15};

Physical Volume("Vol") = {id[]};

Physical Surface("Extr") = {15};
'''

mesh = Gmsh3D(geo + '''
Physical Surface("surf_ges") = {41, 42, 43, 44, 49, 47, 45, 48, 46, 15};

Physical Surface("HX") = {45, 46, 48, 47};
'''
)
submesh = Gmsh2D(geo)

x,y,z = mesh.cellCenters 
X,Y = submesh.cellCenters[..., submesh.physicalCells['Extr']]
Z = numerix.ones(X.shape) * z[0]

tS = CellVariable(name="storage", 
                  mesh=mesh, 
                  value=mesh.x * mesh.y * mesh.z, 
                  hasOld=True)

tSslice = CellVariable(name = 'tSsclice',
                 mesh = submesh)

# interpolate values of tS at positions of tSslice
tSslice[..., submesh.physicalCells['Extr']] = tS(numerix.vstack([X, Y, Z]))

viewer = MatplotlibViewer(vars = tSslice)

在这里，我使用相同的.geo脚本来定义mesh和submesh。我仅将surf_ges和HX物理表面添加到mesh的定义中，因为否则所有这些面也将被导入到submesh中，尽管有效的{ {1}}的值为0，因此它们会掩盖您感兴趣的面孔。

坦率地说，我认为通过3D数据实现切片的一种更好的方法是使用自定义的MayaviClient（例如，请参见Cahn-Hilliard sphere和sphereDaemon.py）或导出使用VTKViewer，然后使用诸如ParaView，VisIt或Mayavi之类的工具呈现数据切片。

在fipy中将PhysicalFace提取为2D网格

1 个答案: