Gridap.jl: Add tags to faces of 3D models

General Usage
1

Hello everyone,
I am new to Gridap.jl. I am creating a 3D model of a cantilever beam to apply a distributed load on the right face, and the left face is fixed.
Do you know how to add tags to LEFT and RIGHT faces ?
Here is my code:

using Gridap

L = 1 # Length of 3D cantilever beam
W = 0.2 # Width of 3D cantilever beam

domain = (0,L,0,W,0,W)
partition = (20,6,6)
model = CartesianDiscreteModel(domain,partition) # Mesh
writevtk(model,"model_3D")

add_tag_from_tags!(labels,"left",....) # How to add tag to LEFT face ?
add_tag_from_tags!(labels,"right",....) # How to add tag to RIGHT face ?

Ω = Triangulation(model)
Γ = Boundary(Ω,tags="right") # I want to a load on this face
reffe = ReferenceFE(lagrangian,Float64,1)
Vₕ = TestFESpace(Ω,reffe,dirichlet_tags="left") # This face is fixed

image
image924×406 27.5 KB

Thank you so much!

2

We’ve usually used Gmsh to generate meshes for Gridap, and Gmsh is pretty flexible in allowing you to tag different features.

3

You can visualize the entity to which tags are affected in the cartesian discrete model in Paraview:

image
image682×765 46.8 KB

5

Thank you. Yes, this method will be more flexible compared to manual tagging in Paraview.

6

Thank you!
Following your suggestion and this post: Add tags to faces of 3D models using CartesianDiscreteModel() · gridap/Gridap.jl · Discussion #1127 · GitHub
I found the solution. We need to include 09 tags for each side.
Here is my final code and the result.

using Gridap
L = 1.0 # Length
W = 0.2 # Width
domain = (0,L, 0,W, 0,W)
partition = (40,12,12)
model = CartesianDiscreteModel(domain, partition)
labels = get_face_labeling(model)
# Tag the left face (x = 0)
add_tag_from_tags!(labels,"left",[1,3,5,7,13,15,17,19,25]) # left face: corners (1,3,5,7); edges (13,15,17,19); others (25)

# Tag the right face (x = L)
add_tag_from_tags!(labels, "right", [2,4,6,8,14,16,18,20,26]) # Right face: corners (2,4,6,8); edges (14,16,18,20); others (26)

writevtk(model,"3D_Problem")

image
image715×755 128 KB

Best regards,

7

At some point I was also looking for the default tags in CartesianDiscreteModel. Now I regularly go back to this txt file:


        3 --- 10 --- 4
     19 |         20 |
   /   13       /    14
 7 --- 12 --- 8      |
 |      |     |      |
15      1 ----| 9 -- 2
 |    17      16   18              ^ y+
 |  /         |  /                 |
 5 --- 11 --- 6                    |       x+
                                   / ------>
                                  /
        3 ---------- 4           v z+
      / |          / |          
   /    | 24    /    |  <-- 21 (back)
 7 ---------- 8      |
 |      |     |   26 |
 |  25  1 ----|----- 2
 |    /  22   |    /
 |  /         |  /
 5 ---------- 6

       ^
       |
      23 (bottom)

(I think this is not documented in Gridap.jl)

8

Thanks for sharing. It makes more sense to me now to understand the way Gridap numbers the tags.