Mesh size variation

Dear everyone,
I am new to Cubit and currently want to mesh my geometry in 3D.
I am already familiar with mesh variation for 2D using bias factor but I find some difficulties in 3D. I have tried to use uniform size but I need to do mesh size variation to save the memory disk for my 3D simulation.
Things I want to do is I want to have the finest mesh size about 1km in my interesting curves and gradually larger as it reaches the edge of the geometry.
Can anyone give me some suggestions on how to start?

Thank you in advance.

Alvina K K

Are you creating a tet mesh or a hex mesh? With a tet mesh, set the sizes on the features of interest and mesh the volume.

bri x 10
surface 5 size .1
surf 3 size 2
vol 1 scheme tetmesh
mesh vol all

You can accomplish the same biased hex mesh by setting a bias on the curves. You have to propagate that bias to other curves in the same direction or set them all manually to create a uniform bias through the volume. If the surfaces are logically 4 sided, that is you can put a mapped mesh on the surface, you can propagate the bias to other curves in the volume using the propagate command.

reset vol 1
curve 1  scheme bias fine size .1 coarse size 2 start vertex 2 
propagate curve bias volume 1 
mesh vol 1

Does that get you started?