# Data structure of mesh for DG methods

Hi, all

When DG methods are employed in the Stokes equation, we tend to use some codes like:

``````mesh = Mesh(geo.GenerateMesh(maxh=0.1, quad_dominated=False))
V = VectorL2(mesh, order=3, dgjumps=True)
n = specialcf.normal(mesh.dim)
u, v = V.TnT()
jump_v = v-v.Other()
a = BilinearForm(V)
a += InnerProduct(mean_grad_u.trans*n, jump_v) * dx(skeleton=True)``````

My question is: for a fixed edge or facet, how do we know its inner element or outer element because we use `jump_v = v-v.Other()`, and further the direction of its unit normal? Are the both consistent?

Best,
Di Yang

Hi,
n and .Other are consistent.

Best
Christopher

How to make uniform triangle mesh on the square [-0.5,1.5][0,2], not regular domain [0,1][0,1]?

Hi Di Yang,

you can make you own python function based on MakeStructured2DMesh in python/meshes.py. You should be able to get the desired effect by just scaling the mesh points appropriately (line 111 of the file).

Best,
Henry

You donâ€™t need to implement the method yourself, see How to make a uniform triangulation on the square domain [-0.5,1.5]*[0,2] - Kunena .

Best,
Christoph