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-   -   Hollow cube creation with the top end open in design modeller (http://www.cfd-online.com/Forums/ansys-meshing/64409-hollow-cube-creation-top-end-open-design-modeller.html)

ram881973 May 10, 2009 20:31

Hollow cube creation with the top end open in design modeller
 
Hello! iam new to ansys design modeller.may pl anyone suggest how to create a hollow cube with top end open.while creating a plane & extruding it is giving solid model.pl help.

ram:)

PSYMN May 11, 2009 09:41

What are you trying to get?
 
Do you want a surface model (5 surfaces) or a thin solid box with an open top?

ram881973 May 11, 2009 23:38

It is thin soild walls(hollow) with top end open.Actually iam modelling a furnace.
pl help me out.

ram

Jules May 12, 2009 14:58

Again: what are you trying to get?
 
Hey ram, to me it's also not quite clear what you are trying to get. Do you want to model the walls themselves (that is the solid walls that PSYMM ist talking about, IMHO), just draw two rectangles/squares on one plane, one inside the other, extrude the outer one first and then extrude the inner and subtract.
If you want to model (mesh) the inside of the box (furnace), a simple extrude from the top face should suffice, because you always have to model the fluid itself, not the structure around it.
Maybe a quick sketch of yours (e.g. in MS paint, or scan a pencil sketch from paper) helps to clarify.

Cheers,

Jules

PSYMN May 13, 2009 10:27

Baffle Surface?
 
If you want a zero thickness structural model, you could create the thin solid box and midsurface it. I think you can also create the 5 surfaces as surfaces, but I have less experience with that.

I am guessing that you oversimplified what you really want to do and that is what has confused us... You probably want a zero thickness baffle? like a furnace made of sheet metal in a larger farfield flow? You want to model the flow around the sheet metal (both sides), but don’t want to model the thickness? At this point DM does not support baffles, but it is a high priority enhancement request for the next release.

In the mean time, you could build your box as a volumetric flow region cut out of your far field. Mark 5 of the sides as walls and the 6th as open. The wall boundary conditions would act as the sheet metal and the opening(s) would allow flow between the volumes.

Another option would be to use a tool like ANSYS ICEM CFD or Fluent GAMBIT that allows for the straight up use of baffles.

ram881973 May 14, 2009 00:20

1 Attachment(s)
Dear Mr.Psymn & Mr. Jules

ThankQ very much for ur interest in clearing my doubt.Iam very sorry for not presenting my doubt clearly.I have attached the 2d and(front view) and 3d geometry for reference.
my plan of work is as follows
1) creating the model of black liquor recovery boiler(furnace).
2) creating the air injection ports and black liquor drop injection nozzles
3)simulating the physical and chemical process(combustion and reduction process)in side the furnace
Actually iam creating the furnace geometry as a boundary of chemical and physical process and for attaching air/liquor ports .
ypu are requested to help me out.

PSYMN May 14, 2009 14:53

questions about doubts...
 
I don’t have time to look into this properly right now… Just a few minutes while a job is running. Maybe Jules or someone else will have a chance.

Don’t get me wrong, I have the utmost respect for engineers who learn English as a second language while still in their home country... But I think there is some terrible English teacher running around the world telling everyone to use the word “doubts” as equivalent to “questions”.

I have worked around the world and seen this as very common on three continents. I have also seen American presenters get very flustered when dozens of people from the audience (at home or abroad) all stand up to express “doubts” regarding their work… Once after my presentation, my manager expressed concern that the audience didn’t believe me, I had to explain my theory about the well traveled, but misguided English teacher.


In English, “doubts” has a very negative connotation. It means you think the other person is either mistaken or outright lying, either way you don’t believe them.


Use the word “questions” instead; unless you really didn’t believe us...;)

ram881973 May 14, 2009 22:31

Quote:

Originally Posted by PSYMN (Post 216127)
I don’t have time to look into this properly right now… Just a few minutes while a job is running. Maybe Jules or someone else will have a chance.

Don’t get me wrong, I have the utmost respect for engineers who learn English as a second language while still in their home country... But I think there is some terrible English teacher running around the world telling everyone to use the word “doubts” as equivalent to “questions”.

I have worked around the world and seen this as very common on three continents. I have also seen American presenters get very flustered when dozens of people from the audience (at home or abroad) all stand up to express “doubts” regarding their work… Once after my presentation, my manager expressed concern that the audience didn’t believe me, I had to explain my theory about the well traveled, but misguided English teacher.


In English, “doubts” has a very negative connotation. It means you think the other person is either mistaken or outright lying, either way you don’t believe them.


Use the word “questions” instead; unless you really didn’t believe us...;)

Dear Mr Psymn
Sorry........ Iam very sorry for using the word "doubt" .As told by u iam not proficient in english and really you have helped me a lot by telling it's meaning and how it hurt's someone inadvertently . But i request you ,if you have time ,pl help me out in solving my modelling problem.Even if you could not find the time,Still i will have great respect in you as you are the first person to respond to my question and shown intrest towards solving my problem.

ThankQ very much
ram

Jules May 15, 2009 19:14

ram, from what I understand you have to model the solid region INSIDE the furnace, because this is where the fluids that you want to simulate, are located.
I'm not too familiar with the design modeller, I did some basic CFX tutorials (the one with flow in a static mixer) using design modeller, but this was years ago. As far as I remember it works like pretty much any solid model CAD tool.
You should make a sketch of the sideview (in design modeller) and extrude it to get the solid model. Then you can make other sketches (circles) and extrude them for the injection ports and nozzles. With any solid you create you also create the bounding surfaces, so you will have these available as boundaries later.
You could also create the geometry in another CAD program and import it.

Besides that, you might want to work through the basic cfx tutorials. After all, it seems to me like the static mixer tutorial is somewhat similar to your problem.

Best wishes,

Jules

PSYMN May 17, 2009 17:09

Agreed
 
I agree, if you just need to model the inside, Jules is right. Actually, I recomend working thru some tutorials anyway. You may just want to start with the basic shape and then imprint the surface features you want on it... You can use the sketch tool in DM.

If you want the thin sheet metal in a larger farfield, look at my earlier post.

Good luck.

Simon


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