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-   -   How can I increase mesh near the pipe wall in 3D (http://www.cfd-online.com/Forums/fluent/45189-how-can-i-increase-mesh-near-pipe-wall-3d.html)

simon fransis June 28, 2007 02:48

How can I increase mesh near the pipe wall in 3D
 
Hi I have 3D pipe geometry I need to increase the mesh near the wall of the pipe so can anyone guide me how can I did this with some details? Knowing that I want a method another thank creating boundary layers because I used it before and not work properly with me?

Thanks a lot for any suggestions Simon Fransis


amir June 28, 2007 04:55

Re: How can I increase mesh near the pipe wall in
 
Dear Simon you can create a smaller cylinder and tehn split your cylinder by it. now you can create increase the mesh near thw wall.(you should mesh outer pipe with a smaller interval) Best Amir

simon fransis June 28, 2007 05:17

Re: How can I increase mesh near the pipe wall in
 
Dear Amir thank you for your reply. I want to comment about your answer If I draw anther cylinder hence I make a thickness to the pipe? Did you mean this or what? Furthermore if I draw smaller cylinder with less diameter the internal diameter of the flow domain will decrease? Do you have another idea?

Simon


amir June 28, 2007 07:27

Re: How can I increase mesh near the pipe wall in
 
Dear simon if you split your cylinder by a smaler cylinder , and mesh those ,gambit asigne interior BC to those ,so indeed you dont have any thickness. i mean small cylinder is only to increase mesh and fluent dont consider it . Best Amir

simon fransis June 28, 2007 10:36

Re: How can I increase mesh near the pipe wall in
 
Amir as i understood from your last answer did you mean I draw interior cylinder with the same length and less diameter? If i did this then should i use unit to combine the cylinders together then mesh them or no?

Thanks a lot Simon


G'bli Gedook June 28, 2007 11:12

Re: How can I increase mesh near the pipe wall in
 
When you split the two cylinders you are merely splitting the mesh regions, not the fluid domain. So the result would be a two regions of different meshes and one fluid domain (controlled by the diameter of the outer cylinder.)

amir June 28, 2007 13:20

Re: How can I increase mesh near the pipe wall in
 
Dear simon draw whit same lenght but whit less diameter . and as i and G'bli said you should split biger whit smaler. dont worry if you have another quastion . we are here. Best Amir

simon fransis June 29, 2007 01:45

Re: How can I increase mesh near the pipe wall in
 
Dear amir and Gedook I want first to express my thankful to both of you. I thought I succeeded with split the cylinders but I face a problem. How can now I mesh the region between the two cylinders? I named the outer cylinder c1 and the inner c2 should I mesh first c1 before c2 or what? When I try mesh c1 the following error appear to me : Error: volume c1 could not be meshed using cooper scheme.

What can I do then?

Thanks Simon


simon fransis July 1, 2007 01:03

Re: How can I increase mesh near the pipe wall in
 
Dear amir and Gedook I want first to express my thankful to both of you. I thought I succeeded with split the cylinders but I face a problem. How can now I mesh the region between the two cylinders? I named the outer cylinder c1 and the inner c2 should I mesh first c1 before c2 or what? When I try mesh c1 the following error appear to me : Error: volume c1 could not be meshed using cooper scheme.

What can I do then?

Thanks Simon


amir July 3, 2007 11:13

Re: How can I increase mesh near the pipe wall in
 
Dear simon It depends on your request. I mean perhaps you want radial mesh or not .perhaps you want mesh several faces whit a deferent spacing and …. but took my advises step by step to reach a …..mesh: 1.split bigger cylinder whit smaller cylinder . 2.create 2 faces that cross cylinders (if your axis of cylinder is in z direction you should create faces in xz and yz planes ) 3.you should cuter (or splinter )faces so create move one face to right (equal whit your bigger radius ) and another to left (equal whit your bigger radius ). 4.split your bigger whit one face and be careful that select 'bidirectional' bottom in split window. 5.now you should split smaller cylinder whit 2faces . (follow previous step ) 6.set all central vertexes on Trielement (to prepare quadrants to use wedge primitive scheme ) 7.mesh inner quadrants of cylinders . 8.mesh outer quadrants of cylinders . There are several method or strategy for mesh your geometry except this one. Best Regards Amir


simon fransis July 3, 2007 11:47

Re: How can I increase mesh near the pipe wall in
 
dear amir I appreciate your assist I think the best way you send me sample of this into my email address : simonfransis@gmail.com

Thanks so much simon


mayur July 4, 2007 07:28

Re: How can I increase mesh near the pipe wall in
 
see if u r wanting hex then u should first mesh the end faces of the cylinders using pave method... the mesh the sides usind map scheme... then volume mesh.

Alternatively u can mesh the Single bigger(original) cylinder using tri surface mesh and create prisms in T-Grid.

simon fransis July 4, 2007 08:19

Re: How can I increase mesh near the pipe wall in
 
Hi mayur Yes i want use hex and i want to concentrated the mesh near the wall this actually the object from my first question I am not familiar too much with 3D its my first time to work with it so I am grateful if you send me a sample as journal file for the method you describe into my email below: simonfransis@gmail.com

REGARDS Simon

mayur July 5, 2007 08:03

Re: How can I increase mesh near the pipe wall in
 
if u want to use hex cells then it is not possible in Tgrid... it can only create prisms for boundary layer...

You will have to take help of size functions then ... there is no need to split the geometry in that case... read something about size functions.. and how to use them.

simon fransis July 5, 2007 09:17

Re: How can I increase mesh near the pipe wall in
 
thanks mayur what section of help i can find in it information about size function? can you give me its number?

Thanks Simon


red lemon July 10, 2007 17:45

Re: How can I increase mesh near the pipe wall in
 
adapt grid using boundary or Y+ in Fluent

simon fransis July 11, 2007 00:03

Re: How can I increase mesh near the pipe wall in
 
how I can use this can you tell me with more details?

Simon fransis


red lemon July 11, 2007 17:35

Re: How can I increase mesh near the pipe wall in
 
go to grid>adapt and choose boundary/Y+ and mark the cells. Choose refine and apply then review the mesh where a hanging node grid will have been generated which can be solved on in Fluent.

simon fransis July 12, 2007 01:55

Re: How can I increase mesh near the pipe wall in
 
OK you mean by this way Fluent will automatically increase the mesh near the wall without the need to do anything in Gambit? Tell me please?

Thanks Simon


red lemon July 15, 2007 17:02

Re: How can I increase mesh near the pipe wall in
 
Yes adapting is done in Fluent and not Gambit and results in a hanging node mesh unless it is a hex dominant mesh with transitional polyhedral cells (converted using Fluent's tpoly utility).


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