# Failure of automatic mesh division，and how to specify the size of a certain direction

Hello everyone, I created a body containing a cylinder, then I tried to divide them into three layers, where each of these three layers has a different mesh size, mainly in the z-direction, but there is an error when dividing them, here are the specifics of the error and the exact process I went through to create it, in addition to that, I have a question, is it possible for cubit to specify the size in a certain direction instead of a square.

``````reset
brick x 200 y 150 z 25
move vol 1 x 100 y 75 z -12.5
brick x 200 y 5 z 5
move volume 2 x 100 y 12.5 z -12.5
brick x 200 y 5 z 5
move vol 3 x 100 y 137.5 z -12.5
frustum z 25 radius 12.5 top 10
move vol 4 x 50 y 75 z -12.5

# SUBTRACT VOL B FROM VOL A
subtract vol 2 from vol 1
subtract vol 3 from vol 1
subtract vol 4 from vol 1

frustum z 25 radius 12.5 top 10
move vol 5 x 50 y 75 z -12.5

webcut vol all plane zplane offset -10
webcut vol all plane zplane offset -15

imprint all
merge all

volume 1 5 6 11 size 1
mesh volume 1 5 6 11

volume 7 8 9 10 size 0.5
mesh volume 7 8 9 10

``````

Hi @sunflower,
you first meshed the top and bottom volumes and after that tried to mesh the middle volumes.

This won’t work if you won’t ensure that the interval count is the same on top and bottom. Just mesh them all together. Cubit does the rest.

If you want to specify the element layers over the thickness, then you could set a scheme and interval for some curves.

``````#!cubit
reset
brick x 200 y 150 z 25
move vol 1 x 100 y 75 z -12.5
brick x 200 y 5 z 5
move volume 2 x 100 y 12.5 z -12.5
brick x 200 y 5 z 5
move vol 3 x 100 y 137.5 z -12.5
frustum z 25 radius 12.5 top 10
move vol 4 x 50 y 75 z -12.5

# SUBTRACT VOL B FROM VOL A
subtract vol 2 from vol 1
subtract vol 3 from vol 1
subtract vol 4 from vol 1

frustum z 25 radius 12.5 top 10
move vol 5 x 50 y 75 z -12.5

webcut vol all plane zplane offset -10
webcut vol all plane zplane offset -15

imprint all
merge all

volume 1 5 6 11 size 5
volume 7 8 9 10 size 2

curve 70 95 108  interval 2
curve 70 95 108  scheme equal

mesh volume all
``````