Mesh study with tree mesh

[ErikQ97]

Hi there,

I am solving PDEs based on DGSEM and tree mesh, and I want to do a mesh study. Is there anyway to define the mesh manually without refinement? Additionally, I am also curious about the refinement principle, how does it work based on initial_refinement_level and n_cells_max?

Thank you!

[andrewwinters5000]

On TreeMesh the refinement is restricted to powers of 2. The initial_refinement_level is the power of 2 for the number of elements in each spatial direction. For example, in two spatial dimensions taking initial_refinement_level = 4 would give a 16 x 16 element mesh. The n_cells_max is used as a cap for how many elements are allowed when using adaptive refinement.

If you want to define a number of elements that is not a power of 2 in each spatial direction, you can use StructuredMesh or P4estMesh. An example in 2D for Structured mesh would be

coordinates_min = (-1.0, -1.0) # minimum coordinates (min(x), min(y))
coordinates_max = (1.0, 1.0) # maximum coordinates (max(x), max(y))

cells_per_dimension = (10, 10)

# Create mesh with 10 x 10 elements
mesh = StructuredMesh(cells_per_dimension, coordinates_min, coordinates_max)

[ErikQ97]

Thanks for your reply! So if I select initial_refinement_level = 4, there will be 16 segments in one dimension? Will that be refined later?

[andrewwinters5000]

This will only be refined if the AMRCallback is used. Otherwise the initial amount of mesh elements will be fixed in time.

[ErikQ97]

Got it. Thank you!