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tmeysam92 August 2, 2012 04:47

Fluent
 
4 Attachment(s)
Hi all,

i have a simple question.

i created a cylinder in ansys modeling. then i sliced it in 4 parts.

i meshed all parts.(conformal mesh)

i used named selection for inlet and outlet(FIG.1).

when i import mesh to fluent, there are 8 walls!!(FIG.2.)

my question is, how the wall is created??? and please tell me, why the walls can not be displayed in fluent(FIG.2.)?
what should i do? i don not want to have walls????
and how can i convert the walls to interior(FIG.3.)?

Bionico August 2, 2012 04:56

Hi,
i think it happened because your fractions of fluid should be in the same part: in Design Modeler select all of them ---> right-click ----> FORM NEW PART.
Otherwise, in your actual situation, you have to create coupled wall between each part :)

flotus1 August 2, 2012 05:15

Why did you split the pipe like this?
The elements in the center of the pipe have a very low quality.
I suggest you use an O-Grid instead.

tmeysam92 August 2, 2012 05:39

Quote:

Originally Posted by flotus1 (Post 375000)
Why did you split the pipe like this?
The elements in the center of the pipe have a very low quality.
I suggest you use an O-Grid instead.

thanks for reply

you right. but the center mesh is not important for me.

any way, my question is why there all walls in fluent????

tmeysam92 August 2, 2012 05:42

1 Attachment(s)
Quote:

Originally Posted by Bionico (Post 374997)
Hi,
i think it happened because your fractions of fluid should be in the same part: in Design Modeler select all of them ---> right-click ----> FORM NEW PART.
Otherwise, in your actual situation, you have to create coupled wall between each part :)

thanks for reply.

i formed new part.
but the mesh changed!!!!!!!!!
i want to have the first mesh.

flotus1 August 2, 2012 05:46

Bionico already gave the correct answer to this.

Although you may not be interested in what happens at the center of the pipe, the whole flow field depends on the result here.

Bionico August 2, 2012 05:56

In the last picture I see that the zone near the circumference has a different colour, and in the Geometry there's a solid and a fluid zone... in the first picture there was only fluid, are you sure you haven't changed anything in the design modeler?

tmeysam92 August 2, 2012 06:07

1 Attachment(s)
Quote:

Originally Posted by Bionico (Post 375011)
In the last picture I see that the zone near the circumference has a different colour, and in the Geometry there's a solid and a fluid zone... in the first picture there was only fluid, are you sure you haven't changed anything in the design modeler?

you right.
i made mistake.

below is the correct picture.

tmeysam92 August 2, 2012 06:09

Quote:

Originally Posted by flotus1 (Post 375010)
Bionico already gave the correct answer to this.

Although you may not be interested in what happens at the center of the pipe, the whole flow field depends on the result here.


i know that the center part is very important.

but my question is about slice tool in design modeler, i mean when i slice different body for generating hexa mesh, in fluent there will be walls???? why???

flotus1 August 2, 2012 06:22

Because when you slice one part, you get two parts. The surface between the two new parts is treated as a wall. I cant think of an answer to the question "why?". It has to be one of the two, interface or wall.
If you do not want this surface to be treated as a wall, freeze the part before slicing and "form new part" from the two parts after slicing. Or switch the boundary condition from "wall" to "internal" in fluent.

Bionico August 2, 2012 06:30

As flotus and I (in the first answer) said, you should put all the parts in one (then you can even rename each of the sub-part). Otherwise fluent create walls and you have to define them in MESH INTERFACE

tmeysam92 August 2, 2012 06:32

Quote:

Originally Posted by flotus1 (Post 375015)
Because when you slice one part, you get two parts. The surface between the two new parts is treated as a wall. I cant think of an answer to the question "why?". It has to be one of the two, interface or wall.
If you do not want this surface to be treated as a wall, freeze the part before slicing and "form new part" from the two parts after slicing. Or switch the boundary condition from "wall" to "internal" in fluent.

if you look at my first thread(FIG.3.), there is no choice for converting wall boundary to internal!!!!! also i don not know why i can not see the walls in fluent display tool?? do you know why???

also if i use FORM NEW PART tool, then i can not mesh the cylinder like FIG.1.

tmeysam92 August 2, 2012 06:50

2 Attachment(s)
Quote:

Originally Posted by flotus1 (Post 375015)
Because when you slice one part, you get two parts. The surface between the two new parts is treated as a wall. I cant think of an answer to the question "why?". It has to be one of the two, interface or wall.
If you do not want this surface to be treated as a wall, freeze the part before slicing and "form new part" from the two parts after slicing. Or switch the boundary condition from "wall" to "internal" in fluent.

as you said, i freeze the part befor slicing, then i sliced, after that i form a new part, finally i meshed, but the mesh is different form first mesh!!!

look at these pictures.

flotus1 August 2, 2012 06:56

Quote:

there is no choice for converting wall boundary to internal
Maybe this is because you had both fluid and solid phase earlier in this discussion.

Quote:

if i use FORM NEW PART tool, then i can not mesh the cylinder like FIG.1
If you click on the button "create mesh" in the ansys mesher, it is not you who creates the mesh but the ansys modeler does it for you. You are no longer in control. One of the advantages is that a mesh like in Fig. 1 is prevented.
If you really want to fully control the outcome of the meshing process, use a meshing tool like ICEM ot Gambit.

Quote:

i can not see the walls in fluent display tool
I really don't know. I am not used to check the mesh in Fluent.

tmeysam92 August 2, 2012 06:59

Quote:

Originally Posted by flotus1 (Post 375023)
Maybe this is because you had both fluid and solid phase earlier in this discussion.

If you click on the button "create mesh" in the ansys mesher, it is not you who creates the mesh but the ansys modeler does it for you. You are no longer in control. One of the advantages is that a mesh like in Fig. 1 is prevented.
If you really want to fully control the outcome of the meshing process, use a meshing tool like ICEM ot Gambit.

I really don't know. I am not used to check the mesh in Fluent.

thank you very much for your reply


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