# 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 don’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