Pipe bend meshing using MultiZone
 

There were some requests on how to produce a quality mesh for a pipe bend using Ansys mesher.
Since the basic procedure can be transferred to similar geometries, I decided to write a beginners tutorial for this purpose.

Geometry

Nothing special here. Create the geometry the way you want.
No need to do splits or face imprints.
When You are done, switch to the the Ansys mesher.
Attachment 28548


Meshing

Step 1
First thing we should always do when creating meshes for CFD simulations is switching the Physics Preference to CFD. This is not mandatory here, but the mesh will generally be much better suited for CFD.
I also switched the relevance center to medium, just to get slightly smaller elements with the default settings.
Attachment 28549

Step 2
Insert a new mesh control method.
Attachment 28550

Step 3
Select the whole volume as geometry for this method.
Attachment 28551

Step 4
Select MultiZone from the method drop down menu.
Attachment 28552


...continued in the next post

Step 5
Insert an "inflation" mesh control.
Attachment 28553

Step 6
Again, select the whole fluid body as geometry.
Attachment 28554

Step 7
Select the outside faces as boundaries for the inflation.
Attachment 28555

Step 8
Choose values appropriate for your geometry and application.
The values I put here are just an example to make the result look good.
You can generate the mesh now, the result will be quite good
Attachment 28556Attachment 28558

...continued in the next post

Step 9
For an even better result, edit the details of the multizone method.
Change the Source/Target selection to manual source and select one of the circular faces of the pipe as geometry.
Thats it. You can now generate the mesh and contemplate the result.
Attachment 28559

Result
Attachment 28560

Many thanks for useful guide

the last step does not seem to work for me, gives the same result which is like the picture you have given before your last step of change to manual and selecting a face...

I followed the steps, but it worked, do you select your first sketch which you sweep it to make model as a source?

my geometry is made in solidworks but i dont think it should make a difference

inflation number of radial elements and in direction of flow
 

hi flotus1,

I created an O-grid like that but for a straight duct. Now I have 2 questions and would appreciate if you could answer them :)
1.) The elements close to the square in the middle of the mesh are pretty
big. How can I set their sizes (like the ratio of the last cell before the
scare and the first cell at the wall should equal 2)
=> Right now my settings are: TransitionRatio=0.8, Number of
Layers=20 and GrowthRate=1.2
2.) I also want to create an Inflation in flow direction of the pipe, but
everytime I try that the inflation for the O-Grid dissapears :/

I hope you can help me :)
Thanks, greetings from South Germany:)

Is there any other method of producing same type of mesh in ANSYS only?,
Because this method is taking so much of time in my personal computer having 8 GB RAM.

Please help me out. I am stuck with this.

I think this is the only way to get such kind of mesh.
If your geometry is big and mesh is fine then it will take time, you cant do much about it.

hello,

could you please explain me which is the effect of the multizone method?
what happens if you don't apply this method and which criteria do you use to select the manual source and target faces?
many thanks in advance.

Hi delplatl,

The best way to get answer to this question is reading about it.
Use help section and read about all type of methods and make a small geometry and try to mesh it with different Mesh methods to get complete idea.

Cheers
KAPI

Effect of mesh size on the convergence
 

Hi all,

Is there any effect of mesh size on the convergence of solution in FLUENT.

I mean to say that in my problem I have divided the entire cylindrical bend into very fine mesh but solution is not being converge but if I reduce the number of mesh or in other words increase the size of mesh element then solution is being converged.

Am I doing right thing or should I try try to change any other parameter keeping very fine mesh.

Please help me out.