[shayan_mv]

Hello
I have a ribbed rectangular channel with two blocks on upper wall as blow:

http://imageshack.us/photo/my-images...hot001rxd.jpg/

I have performed boundary layer mesh as can be seen in the image,but I don't know how to do map mesh for the face!Is it necessary do the mesh for edges first? if so,what will happen for the boundary layer meshes?
How can I have a uniform mesh(with rectangular cells)?

Thanks

shayan

[Far]

don't do this unless you want the hybrid mesh. This geometry is easily mappable. Make few split on the straight line and create edge between vertices. Set the no of nodes on vertical edges, grading scheme and ratio of 1.1-1.2

[shayan_mv]

Originally Posted by Far

don't do this unless you want the hybrid mesh. This geometry is easily mappable. Make few split on the straight line and create edge between vertices. Set the no of nodes on vertical edges, grading scheme and ratio of 1.1-1.2

Thanks for your response.
If i do that,I'll have more than one edge in inlet.So, I should define more than one "inlet velocity" as boundary condition and also the same condition for "pressure outlet". Is this OK?!

[-mAx-]

you can define many edges as part of ONE boundary condition.
Your domain should be automatically set as mappable. If not, follow Far's advice.
If you don't split your domain, enable "internal continuity" option in the boundary layer panel

[shayan_mv]

Originally Posted by -mAx-

you can define many edges as part of ONE boundary condition.
Your domain should be automatically set as mappable. If not, follow Far's advice.
If you don't split your domain, enable "internal continuity" option in the boundary layer panel

Thanks Max
I did what you said,and I got the following result:

http://imageshack.us/photo/my-images...shot002td.jpg/

As you can see in the picture, after "map mesh" the mesh is disorder! I can make it fix by making the interval size smaller,but I don't really need to do that.I just want to have denser mesh near ribs and upper wall and to have the rest of face with larger mesh size! what shall I do now,Max?
thank you

[Far]

Like this?

[shayan_mv]

Originally Posted by Far

Like this?

exactly.I want this! How did you do? I'm just beginner ,May I ask you to show me the steps that you have done...
Thank you very much

[shayan_mv]

Originally Posted by Far

Like this?

I know that there are different techniques of doing the mesh,but I am looking for the one that I can reach convergence in acceptable iteration.And also get good results out of that e.g. velocity vectors, Nusselts Number,...

[Far]

First mesh was made in ICEM, which allows me to make the mesh in very few clicks and I just used the O-grid and every thing else is outcome. Whereas the pics below (similar to ICEM mesh) shows the mesh created by Gambit a d requires some geometric operations.

Download gambit file from this link : https://www.dropbox.com/s/05034x33i4...ed_channel.dbs

[shayan_mv]

Originally Posted by Far

First mesh was made in ICEM, which allows me to make the mesh in very few clicks and I just used the O-grid and every thing else is outcome. Whereas the pics below (similar to ICEM mesh) shows the mesh created by Gambit a d requires some geometric operations.

Download gambit file from this link : https://www.dropbox.com/s/05034x33i4...ed_channel.dbs

Thank you so much, I think I should make many faces and mesh each one as I want

regards

[Far]

Youtube clip is currently being processed and will post link, once it is done. Every thing was done in gambit, since you are using gambit

[Far]

Youtube video link :

http://www.youtube.com/watch?v=CfOGD...ature=youtu.be

[shayan_mv]

Originally Posted by Far

Youtube video link :

http://www.youtube.com/watch?v=CfOGD...ature=youtu.be

Dear Far
The video is not available!

[Far]

Yeah, there was some error in uploading and done again. see this link:

https://www.youtube.com/watch?v=Gub1Kbcup2k

[shayan_mv]

Originally Posted by Far

Yeah, there was some error in uploading and done again. see this link:

https://www.youtube.com/watch?v=Gub1Kbcup2k

Thanks a a lot dear Far. I got nearly good results...

My problem was converged after 1428 iteration! May I ask you that what is the main reason? ( I think it is not acceptable)

Regards

Shayan

[Far]

Originally Posted by shayan_mv

Thanks a a lot dear Far. I got nearly good results...

My problem was converged after 1428 iteration! May I ask you that what is the main reason? ( I think it is not acceptable)

Regards

Shayan

If results are good then why you are not satisfied? Which version of fluent you are using?

[shayan_mv]

Originally Posted by Far

If results are good then why you are not satisfied? Which version of fluent you are using?

Well, in comparison with the previous examples that I have done ,my problems were converged less than 300 iteration !

I use "Fluent 6.3.26"

[Far]

It was the similar case? If not then we cannot compare them!!! This may be due to mesh problem, specially the transition between different blocks (in gambit it is face). So try to make the mesh as smooth as possible and specially at the different faces boundaries there should be slow transition and same cell size on both sides of common edge. Moreover you should make the dense mesh in the regions where you expect the separation and strong gradients.

I also recommend you to make the mesh refinement study by making the successive refined meshes to conclude mesh effects on results.

In short:

1. Mesh should be fine enough

2. Should be smooth as possible

[shayan_mv]

Originally Posted by Far

It was the similar case? If not then we cannot compare them!!! This may be due to mesh problem, specially the transition between different blocks (in gambit it is face). So try to make the mesh as smooth as possible and specially at the different faces boundaries there should be slow transition and same cell size on both sides of common edge. Moreover you should make the dense mesh in the regions where you expect the separation and strong gradients.

I also recommend you to make the mesh refinement study by making the successive refined meshes to conclude mesh effects on results.

In short:

1. Mesh should be fine enough

2. Should be smooth as possible

OK. Thank you very much. you guide very exact. I appreciate that.

I just could not get:
1. "Nusselt Number" plot against "Re or Position"
2. " Friction factor" plot against "Re"

[Far]

Refer to some good reference see where they plotted these values or on which plane or line? Then this can be done in Fluent or CFD-post or techplot!