Routines to initialize reference element operators, physical mesh arrays, and connectivity for nodal discontinuous Galerkin (DG) methods. Codes roughly based on Nodal Discontinuous Galerkin Methods by Hesthaven and Warburton (2007). Original port from Matlab to Julia by Yimin Lin.
This package is registered, so you can install it via ] add StartUpDG
.
Variables are contained within structs rd::RefElemData
and md::MeshData
. These structs contain variables from Globals1D, Globals2D, Globals3D
in the Nodal DG book codes. Variables can be unpacked using @unpack
.
using StartUpDG
# polynomial degree and mesh size
N = 3
K1D = 8
# init ref element and mesh
rd = RefElemData(Tri(),N)
VX,VY,EToV = uniform_mesh(Tri(),K1D)
md = MeshData(VX,VY,EToV,rd)
# Define a function by interpolation
@unpack x,y = md
u = @. 2 + .5*exp(-100*(x^2+y^2))
# Compute derivatives using geometric mapping + chain rule
@unpack Dr,Ds = rd
@unpack rxJ,sxJ,J = md
dudx = (rxJ.*(Dr*u) + sxJ.*(Ds*u))./J