Problem identifying field of profile
 

Hi people!

I am a new user in fluent and at the moment I am working on a cfd analysis of an stirling engine, actually I'm defining the motion of the pistons by using a transient profile instead of a UDF. I wrote these profiles first in notepad and saved this with .prof or .ttab extension and read it into fluent. When used the display zone motion and mesh motion dialog box to preview each zone, a message appeared saying Warning: Can't identify any field of profile...
No motion specified.
Is it due to a wrong profile specification, or a wrong center of gravity orientation?

Does anyone know about that?
Thanks in advance
:)

Hi:

You need to have a compiler installed (for example visual studio) and save your code as *.c. Then compile the file in fluent and build the library (see udf manual).

Thanks GK-mech for your Reply

You are talking about DEFINE_PROFILE as a UDF?, I refer to a profile file, I wrote a profile file with the profile format in a transient form and fluent read it, indeed it appeared in the drop down list in the dynamic mesh zone dialog box, I assigned it to a face zone as a rigid body motion in motion attributes.


It is my transient tab profile, may be it has an structure problem or it has a conflict with the center of gravity orientation and location, can you help me with it? thanks in advance.

vinletexp 2 51 1
time u
0.00000 3.77357
0.00100 3.30996
0.00200 2.76185
0.00300 2.14237
0.00400 1.46709
0.00500 0.75342
0.00600 0.01998
0.00700 -0.71397
0.00800 -1.42920
0.00900 -2.10702
0.01000 -2.72995
0.01100 -3.28229
0.01200 -3.75078
0.01300 -4.12517
0.01400 -4.39878
0.01500 -4.56887
0.01600 -4.63681
0.01700 -4.60797
0.01800 -4.49126
0.01900 -4.29830
0.02000 -4.04242
0.02100 -3.73749
0.02200 -3.39685
0.02300 -3.03245
0.02400 -2.65422
0.02500 -2.26983
0.02600 -1.88469
0.02700 -1.50212
0.02800 -1.12368
0.02900 -0.74952
0.03000 -0.37881
0.03100 -0.00999
0.03200 0.35877
0.03300 0.72934
0.03400 1.10328
0.03500 1.48148
0.03600 1.86386
0.03700 2.24893
0.03800 2.63347
0.03900 3.01221
0.04000 3.37760
0.04100 3.71981
0.04200 4.02701
0.04300 4.28591
0.04400 4.48263
0.04500 4.60380
0.04600 4.63766
0.04700 4.57514
0.04800 4.41067
0.04900 4.14264
0.05000 3.77357

I am not really sure how this approach works. I would recommend writing a UDF for the motion (if you know the function).

transient profile
 

Hi.
I am modeling a similar problem. A piston that moves inside a cylinder. I want to use transient profiles for moving mesh, so i wrote a profile and loaded into fluent, and hooked it in the "motion UDF/profile" in the moving mesh section. But as i run the simulation i get the following massage " Warning: Can't identify any field of profile piston. No motion specified".
As if boundary did not understand the profile.
I'd appreciate if anyone could help me with this
:D

Velocity profile solved!
 

Hi Members!

I solved it, thanks to THE LORD!

The last year jiji:)


You have first to write a notepad file with the velocity profile data, showing the time and the velocity components, for example:


vexp1200 3 1001 1
time v_x v_y
0.00000 1.34043 1.34043
0.00100 0.84353 0.84353
0.00200 0.32755 0.32755
0.00300 -0.19387 -0.19387

The first line showing the name of the profile, then the number of columns, the number of fields 1001 and 1 for periodic profile.
The first column is the time, the second column the x component of the velocity and the third, the y component.

Finally you have to save it as .dat or .ttab file and set it up in Fluent as profile.