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varghese May 3, 2002 05:01

Making boundary profile on a surface in xz- plane
Hai Friends,

I have to make a boundary profile for a surface lying in xz-plane on a 3D geometry. I encountetr the following problem in doing so:

In order to define a point, line or mesh profile, one has to define x,y fields necessarily, along with the different variable fields as required. The z-field is reserved for definition of the profiles in 3 dimensions.

In the current problem, I rather have to make a profile for a surface lying in the x-z plane.

Can I change the default dimension definitions in Fluent?

Or is there any other way to solve the problem? I have some data available from experiments for the boundary values, from which I want to generate a complete boundary profile for the surface in xz-plane.

I want to be helped in this problem.



Alex May 3, 2002 05:45

Boundary Profile/Plane
Hi Varghese,

you surely know that y profile looks like (my_prof point 3) (x 1 2 3) (y 1 1 1) (z 1 2 3) (my_var 4 5 6) )

or something like that. From what I got you 1) are working in 3D 2) want to set a BC as profile on a XZ plane 3) want to use experiment data

I'll suggest to 1) create a file with the following content (my_profile_name point nbx_of_point) (x in line or colum put all the x coordinates) (y '' '' '' '' y coordinates, they should be all constant since you are working in XZ) (z '' '' '' '' z coordinates, make sure that they corresond to the x coordinates) (my_var '' '' '' my_var values) )

read the profile with FILE/READ-PROFILE>.

Profile is interpolated automatically by FLUENT. Export a TECPLOT file from your boundary to see if it worked properly or not( do not try contour it's crap!!!).



varghese May 3, 2002 07:14

Re: Boundary Profile/Plane
Dear Alex,

Thank you for responding to my request.

I think, I must clarify the problem little more, to make the issues involved little more clear.

I have experimental data not over the face, but rather on two edges defining that face, in xz plane. My intention is therefore first to create a profile for the face, independently of the 3D geometry. And use that, as the boundary condition on the face in xz-plane, in the 3D problem. i.e., I have to create a 2D face-profile from a line profile, to be used as boundary condition for a 3D problem.

It is the realization of the first step, which is invariably related to the final step that poses the problem. In other words, that I have to generate a profile on a face in xz plane, which is a part of a 3D geometry, from the data points on the edges of that surface, proves to be a difficult programme for me.

How to get around it?

Thank you for the further suggestions,


Alex May 3, 2002 07:36

1D to 2D?
Hi V,

yep sorry for the misunderstanding... I should read it more carefully.

so is the following closer to your issue.

1)you have a face(boundary) onwhich you want to apply a profile 2) you only have the value on 2 edge of the face 3) you want to create a profile from the info of those 2 edges

OK sounds like an interpolation to me.

If the edges are parallel I would suggest to do a linear interpolation Edge 1 --> | x | <--Edge 2 total lengt= L my_val(x)=x*(my_val(edge1)-myval(edge2))/L + my_val(edge1) and this for a constant z

If they are orthogonal... Edge 1 --> | (x,y) _ <-- Edge2

my_val(x,y)=my_val(x , y=0 i.e. on edge2)+ y (my_val(x=0 i.e. on edge1,y)-my_val(x=0 i.e. on edge1, y=0 intersection)

Ok it's confusing but I'm sure that a drawing would ease it all.

Did I get the problem this time?


varghese May 3, 2002 08:01

Re: 1D to 2D?
Dear Alex,

Yes, I understand my problem exactly; thank you for that.

But now, I fail to understand your answer!

I get the idea that I must do some interpolation from one edge to the other. But which part of Fluent will help me to implement interpolation. I have never used that facility. Thank you for this new information.

I am waiting for your reply,


Alex May 3, 2002 08:21

Fortran or C++ or EXEL
Hi Varghese,

Why not using one of those software for your interpolation? I doubt that FLUENT can handle it properly.

For my breif explanation, I fairly understand that it's not easy to understand it...

Main idea is to try to use the information you have to fill the grid. After you can even use a spline if you want. Problem being I don't really klnow how to make my previous reply clearer.



varghese May 3, 2002 08:38

Thank you!
Dear Alex,

Thank you very much.

I understood the idea behind your answer but doubted that there exists some functionality which I have never explored.

Don`t be sorry for your answer, it is crystal clear. Problem was that I expected something inside Fluent.

Be happy and enjoy life!!


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