Named selections not seen in Fluent

theHumbleOne · November 21, 2014, 15:35

Hello,

I'm working in Workbench 15.0.7 using ANSYS DesignModeler, Mesher and Fluent. My problem is that I can't see in Fluent four named selections (4 separate surfaces; frozen bodies) created in DesignModeler or Mesher (tried both). What is strange, the fifth named selection appears normally. It is a surface as well, but not the separate body (wall of a cylinder).

I hope I'm not repeating a question. I searched forums and couldn't find an answer.

Ticking 'Named selections' in Workbench->Tools->Options->Geometry import didn't work for me.

Any suggestions?

theHumbleOne · November 23, 2014, 07:26

I found this topic
http://www.cfd-online.com/Forums/ans...ch-fluent.html
which might be the closest one to what I'm searching for. But still it's not all.

I want to have 4 independent surfaces in a fluid box and give them 'fan' BCs in Fluent. As I mentioned before, I can't see them in Fluent, even if create named selections from them.

The problem seems to consider surface bodies (apparently Fluent does not accept them somehow), but how am I supposed to solve it?

Kokemoor · November 24, 2014, 10:23

Surface bodies are for 2D simulations, and need to all be in the same plane. For 3D simulations, Fluent is looking for solid bodies. Try creating a solid body from your surfaces and making named selections for the faces of that body.

theHumbleOne · November 25, 2014, 18:37

Thank you very much. That's what I finally started to suspect.

Thank you for advice also, but now I have another, probably basic, problem. I wanted a flat fan 'hanging' in the middle of fluid body. Now, I have to create a body inside the body.
What this fan-body should be like? I guess fluid (right?), but where should I apply a 'fan' BC (e.g. if it is a cylinder - interior or one of the walls)?
If it is a fluid, I encounter another problem - without uniting/adding materials of the bodies, fluid in a symulation won't flow between them.

I know these are basics, but I can't learn anything helpful from manuals or forums.

Kokemoor · November 26, 2014, 12:15

It's hard to say without more information on your problem, but hopefully I can give you some guidance to play around and get exactly what you're looking for. If you put a BC on the wall directly, you'll have an inlet with no outlet. If you want to circulate flow in a closed domain, you'll need an outlet somewhere. If this is like a ceiling fan, for example, you want a cylinder shape removed from the body whose ends will be an inlet and an outlet. The easiest way to do this in DesignModeler is to use the cylinder primitive and either Cut Material from the domain material or Create Frozen and use a Boolean Subtract to remove the cylinder from the domain. You should only have one solid body: the shape of the domain but with a cylinder removed.

theHumbleOne · November 27, 2014, 17:36

Ok, let's get it straight.
Ceiling fan is a really good comparison to what I want to create. Let's say that I really want to create a ceiling fan in a closed room.
I don't fully understand you so please, choose what you meant from one of the options below or create your own.

1. DM: I create a fluid box. Then, I create a frozen cylinder body inside, use Boolean substract with deleting tool bodies. I end up with a fluid body with a cylinder hole inside.
Fluent: I give an intake-fan BC to one wall of a cylinder hole and exhaust fan to the another. I run calculation.

2. DM: Same as previously, but i don't delete the tool body (cylinder).
Fluent: BCs are given to cylinder's walls, not hole's.
2a. Cylinder is fluid.
2b. Cylinder is solid.

To tell the truth I tried all of these and none worked. What's wrong here?

Kokemoor · December 1, 2014, 10:18

Option 1 sounds right. In what way did it not work?

theHumbleOne · December 5, 2014, 06:15

Well, I could't get proper flow through the body-fan. But it's possible that I failed to define BCs properly.

Anyway, I stopped trying this one because in the meantime I found out how to transfer surfaces to Fluent.
In Fluent 15.0 there is a kind of a bug. In ANSYS Meshing -> Mesh -> Details of Mesh -> Advanced you have to change Element Midside Nodes from "dropped" to "program controlled".

The only problem is that surfaces appearing in Fluent are counted as one body called "baffle" (named selectons given in DesignModeler are suppressed in Mesher -> in Mesher you can't select this geometry -> finally, it appears in Fluent as described). So it looks to me that you can't give various BCs to each of them. For me it's not a problem, therefore i don't examine it any more.

Thanks for help.

PS I'm not sure, but had an impression, that in this approach joining bodies in one part was crucial.

November 21, 2014, 15:35	Named selections not seen in Fluent	#1
theHumbleOne New Member Michał Join Date: May 2014 Posts: 12 Rep Power: 11	Hello, I'm working in Workbench 15.0.7 using ANSYS DesignModeler, Mesher and Fluent. My problem is that I can't see in Fluent four named selections (4 separate surfaces; frozen bodies) created in DesignModeler or Mesher (tried both). What is strange, the fifth named selection appears normally. It is a surface as well, but not the separate body (wall of a cylinder). I hope I'm not repeating a question. I searched forums and couldn't find an answer. Ticking 'Named selections' in Workbench->Tools->Options->Geometry import didn't work for me. Any suggestions?

November 24, 2014, 10:23		#3
Kokemoor Senior Member Andrew Kokemoor Join Date: Aug 2013 Posts: 122 Rep Power: 13	Surface bodies are for 2D simulations, and need to all be in the same plane. For 3D simulations, Fluent is looking for solid bodies. Try creating a solid body from your surfaces and making named selections for the faces of that body. theHumbleOne likes this.

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November 23, 2014, 07:26		#2
theHumbleOne New Member Michał Join Date: May 2014 Posts: 12 Rep Power: 11	I found this topic http://www.cfd-online.com/Forums/ans...ch-fluent.html which might be the closest one to what I'm searching for. But still it's not all. I want to have 4 independent surfaces in a fluid box and give them 'fan' BCs in Fluent. As I mentioned before, I can't see them in Fluent, even if create named selections from them. The problem seems to consider surface bodies (apparently Fluent does not accept them somehow), but how am I supposed to solve it?

November 25, 2014, 18:37		#4
theHumbleOne New Member Michał Join Date: May 2014 Posts: 12 Rep Power: 11	Thank you very much. That's what I finally started to suspect. Thank you for advice also, but now I have another, probably basic, problem. I wanted a flat fan 'hanging' in the middle of fluid body. Now, I have to create a body inside the body. What this fan-body should be like? I guess fluid (right?), but where should I apply a 'fan' BC (e.g. if it is a cylinder - interior or one of the walls)? If it is a fluid, I encounter another problem - without uniting/adding materials of the bodies, fluid in a symulation won't flow between them. I know these are basics, but I can't learn anything helpful from manuals or forums.

November 26, 2014, 12:15		#5
Kokemoor Senior Member Andrew Kokemoor Join Date: Aug 2013 Posts: 122 Rep Power: 13	It's hard to say without more information on your problem, but hopefully I can give you some guidance to play around and get exactly what you're looking for. If you put a BC on the wall directly, you'll have an inlet with no outlet. If you want to circulate flow in a closed domain, you'll need an outlet somewhere. If this is like a ceiling fan, for example, you want a cylinder shape removed from the body whose ends will be an inlet and an outlet. The easiest way to do this in DesignModeler is to use the cylinder primitive and either Cut Material from the domain material or Create Frozen and use a Boolean Subtract to remove the cylinder from the domain. You should only have one solid body: the shape of the domain but with a cylinder removed.

November 27, 2014, 17:36		#6
theHumbleOne New Member Michał Join Date: May 2014 Posts: 12 Rep Power: 11	Ok, let's get it straight. Ceiling fan is a really good comparison to what I want to create. Let's say that I really want to create a ceiling fan in a closed room. I don't fully understand you so please, choose what you meant from one of the options below or create your own. 1. DM: I create a fluid box. Then, I create a frozen cylinder body inside, use Boolean substract with deleting tool bodies. I end up with a fluid body with a cylinder hole inside. Fluent: I give an intake-fan BC to one wall of a cylinder hole and exhaust fan to the another. I run calculation. 2. DM: Same as previously, but i don't delete the tool body (cylinder). Fluent: BCs are given to cylinder's walls, not hole's. 2a. Cylinder is fluid. 2b. Cylinder is solid. To tell the truth I tried all of these and none worked. What's wrong here?

December 1, 2014, 10:18		#7
Kokemoor Senior Member Andrew Kokemoor Join Date: Aug 2013 Posts: 122 Rep Power: 13	Option 1 sounds right. In what way did it not work?

December 5, 2014, 06:15		#8
theHumbleOne New Member Michał Join Date: May 2014 Posts: 12 Rep Power: 11	Well, I could't get proper flow through the body-fan. But it's possible that I failed to define BCs properly. Anyway, I stopped trying this one because in the meantime I found out how to transfer surfaces to Fluent. In Fluent 15.0 there is a kind of a bug. In ANSYS Meshing -> Mesh -> Details of Mesh -> Advanced you have to change Element Midside Nodes from "dropped" to "program controlled". The only problem is that surfaces appearing in Fluent are counted as one body called "baffle" (named selectons given in DesignModeler are suppressed in Mesher -> in Mesher you can't select this geometry -> finally, it appears in Fluent as described). So it looks to me that you can't give various BCs to each of them. For me it's not a problem, therefore i don't examine it any more. Thanks for help. PS I'm not sure, but had an impression, that in this approach joining bodies in one part was crucial.