[amirhashemi]

Hello. I am a beginner in working with Gambit. Can any one guide me to mesh a 3d triangular T-junction properly with Gambit 2.4.6?

[-mAx-]

what do you mean with "3d triangular"?
Tetrahedral elements?

[amirhashemi]

Hi. A rectangular T-Junction consists of two channels with rectangular cross section that cross each other and form a T-Junction. I have created two blocks with gambit 2.4.6 and united them together, but I don't know exactly which procedure must be followed to mesh the total volume properly. (I have already studied the tutorial of modeling a 3 pipe intersection (3d), but the geometry and interface of that is different from my job)

[-mAx-]

display some pictures.
Do you want to mesh your geometry with thetrahedral elements (unstructured) or full hex (structured)?

[amirhashemi]

Dear max,

Let me describe from beginning. I want to model a mixing junction as shown in attached schematic diagram. cold and hot air flow into the junction and leave it as a mixture. I want to model this and find velocity and temperature distribution in the mixing area.

I have created two blocks and united them together as shown in the attached photo (taken by mobile phone from the computer monitor)

will appreciate if you advise:

1 whether the procedure for creating the geometry is correct

2 what type of meshing best fits this geometry. May i proceed with automatic meshing for the whole volume or as described in the 3d pipe intersection tutorial, i must decompose the geometry,apply boundary layers at walls, mesh separated volumes one by one and ...

regards

[-mAx-]

for this geometry you don t need to decompose anything.
Such a geometry is meshed with hexa very quickly.
On the front face there are 2 surfaces, which you could merge
Same on back face

[amirhashemi]

Thank you so much for your guidance. i tried to merge the two volumes but the message was: "the volumes are disconnected". when trying to merge the front faces, similar message was shown. I have already united the two volumes; is it necessary to merge them as well?

without merging, i proceeded with meshing the united volume with the setting (element: Hex type: Map). when meshing finished, i examined the mesh and the result is seen in attachment. as it can be seen in the skewness diagram, there is just one green bar. Does this show a good result for meshing or not?

[-mAx-]

Your volumes are disconnected, and it is not good because your fluid will stop where volumes are disconnected.
As your geometry is pretty simple, I would restart from scratch:
> create front face (xy) in 2d
> sweep front face in z direction for having 3d volume
> mesh
> apply your bc
that's it

[amirhashemi]

Dear max,

pls tell me to which section of gambit i should refer for sweeping one face and creating a volume with that?

the 2nd thing is that i require to specify the symmetry surface so that i can make contour display with fluent in this surface. may I create half the volume in the gabmit and specify one face as the symmetry or there is any other procedure ?

regards

[-mAx-]

https://www.sharcnet.ca/Software/Gam...mg0205.htm#406

You can use symmetry if your BC allow you to use it, but if you only want to display your result on this "surface", you only have to create a "slide" in Fluent.
If I can good remember, it should be done with iso-surface
https://www.sharcnet.ca/Software/Flu...tg/node353.htm

[amirhashemi]

dear max,

would you please guide me how i can plot changes of one property (like temperature) in the center line of the inlet surface in the modeled T-junction (the red line in the attached photo) in fluent 6.3.26 ?

thanks

[-mAx-]

https://www.sharcnet.ca/Software/Flu...tg/node361.htm

[amirhashemi]

thanks. it helped me.

I have already created symmetry surface and know how to display contours on the surface. What i don't know is how to display contour on a section of this symmetry surface separated by two parallel lines (I mean section of the surface bounded by two parallel vertical lines). Pls guide.

[-mAx-]

if you already know how this section looks like, then create it in gambit and assign it as interior.
You should be able to select it later in fluent for postprocessing