adjusted mesh size in particular direction

Hi,

I want to generate triangular mesh for concentric cylinder with a thin membrane between inner and outer region:
My input file :

---

algebraic3d
solid cube1 = orthobrick (0, 0, 0; 1400, 1400, 800);
solid cyl1 = cylinder (700, 700, 0; 700, 700, 800; 200.0);

solid dom1=cyl1 and cube1;

solid cube2 = orthobrick (0, 0, 0; 1400, 1400, 800);
solid cyl2 = cylinder (700, 700, 0; 700, 700, 800; 210);
solid gab2= cyl2 and cube2;

solid dom2= gab2 and not dom1;

solid cube3 = orthobrick (0, 0, 0; 1400, 1400, 800);
solid cyl3 = cylinder (700, 700, 0; 700, 700, 800; 700);
solid gab3= cyl3 and cube3;

solid dom3= gab3 and not dom1 and not dom2;

tlo dom1 -col=[1,0,0];
tlo dom2 -col=[0,1,0];
tlo dom3 -col=[0,1,0]- transparent;

---

The coarse mesh looks like this:
drive.google.com/open?id=1FX0AJ71svwhZC9cd4WlG-6dURP6enVe5

and to simulate the "physics" that iam interested in, i need to refine the mesh near the membrane, so it looks like this:
drive.google.com/open?id=1LISFB0zoEPibIXDX4y57ZOZ7urS03UeG



The number of mesh is too large and i know the change of physics quantity iam interested is signifiicant only in radial direction. Is there a way to refine mesh only in particular direction, in my case in radial direction? This way i can save lots of computational time and resource.


(Edited :
I could make more multiple regions and mesh them later to look like this :
drive.google.com/open?id=10nY9n2CtW4su6HPLca9BJ32DmEZ659Qr

But when i tried to increase the length of cylinder, the mesh generation took forever)

Thanks,
Alex

[attachment=undefined]coarse.png[/attachment]

Hi Alex,

You should use prismatic elements for that, so you can use the CloseSurface and ZRefinement features. With this you can slice the prismatic elements to get a refinement only in radial direction. This is a python script for that:

Hi,
be careful here with the z-refinement, it does not go together with curved elements well. But you can use a couple of cylinders for the shell, if needed.
Joachim

Hi christopher,

Thanks for your help with the info of slicing feature, it works well for the previously quoted parameters. I tried to play and double the cylinder length from 800 to 1600, it generated mesh with "too large" zmax

drive.google.com/open?id=1uNvneVM9qF8_ds8Avv4h-ae5x8tZoakw

The modifed part of input:

---

cube1 = OrthoBrick(Pnt(0,0,0), Pnt(1400,1400,1600))
cyl1 = Cylinder(Pnt(700,700,0), Pnt(700,700,1600),200)
dom1 = cyl1 * cube1
cyl2 = Cylinder(Pnt(700,700,0), Pnt(700,700,1600),210)
gab2 = cyl2 * cube1
dom2 = gab2 - cyl1
cyl3 = Cylinder(Pnt(700,700,0), Pnt(700,700,1600),700)
gab3 = cyl3 * cube1
dom3 = gab3 - cyl2

---

i must have done something wrong here, would you please help to take a look at this?

Thanks,
Alex

you have to set a bounding-box for the geometry as follows. Default values are +/-1000

...
geo.CloseSurfaces(cyl1,cyl2,slices)
geo.SetBoundingBox(Pnt (-2000, -2000, -2000), Pnt(2000, 2000, 2000))
ngmesh = geo.GenerateMesh(maxh=100)

Hi Joachim,

that works, thank you.

Alex