CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

Troubleshooting probe and average functions with Angular Velocity

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 28, 2009, 14:17
Question Troubleshooting probe and average functions with Angular Velocity
  #1
New Member
 
Join Date: Jul 2009
Posts: 4
Rep Power: 17
siardica is on a distinguished road
LIBRARY:
CEL:
EXPRESSIONS:
radius = 2 [m]
prevAngVel = (probe(Velocity u )@omegaPt)/radius
timestep = .002 [s]
inertia = 40 [kg * m^2]
curAngVel = prevAngVel + (torque()@Blades * timestep / inertia)
END
END
END

omegaPt is defined as a user point located on the outer perimeter of a rotating domain.

The rotating domain is set to rotate at angular velocity curAngVel.
CFX-Pre returns no errors.


Solver returns:
"Error processing expression 'Angular Velocity'.
The expression is invalid because:
Velocity u is not available for use in this term
Error processing expression: Angular Velocity = curAngVel"

I get this error with every combination of variable and probe or average function I can think of. Having a dumb blonde moment... what am I missing?
siardica is offline   Reply With Quote

Old   July 29, 2009, 08:01
Default
  #2
Senior Member
 
Join Date: Apr 2009
Posts: 531
Rep Power: 21
stumpy is on a distinguished road
I think that Angular velocity is just not allowed to be a function of the fluid velocity. If you look in the VARIABLES file in <install root>/<version #>/CFX/etc/ and search for "Angular Velocity" it will tell you what variable this can be a function of - i think it's called "Dependency List". Now you could try editing this file to comment out the dependency list, and there's a at least a chance it will work, but it may not. The work around is probably to make an algebraic additional variable equal to probe(u)@omegaPt, then make the Angular Velocity a fn of the AV.
stumpy is offline   Reply With Quote

Old   July 29, 2009, 16:02
Default
  #3
New Member
 
Join Date: Jul 2009
Posts: 4
Rep Power: 17
siardica is on a distinguished road
You are officially my hero for the day -- just added velocity to the list of dependencies in the rules file and it worked like a charm. Thanks so much!
siardica is offline   Reply With Quote

Old   July 29, 2009, 20:13
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Hi:

Be very cautious doing this. The variable is probably not in the list of dependencies for good reason! I suspect the influence of variable velocity is not correctly taken into account. I would do a careful validation of this before using it.

It sounds like a great idea, just check it works before you do anything important.

Glenn Horrocks
ghorrocks is offline   Reply With Quote

Old   July 13, 2011, 10:26
Default
  #5
New Member
 
Join Date: May 2010
Posts: 9
Rep Power: 16
pingub is on a distinguished road
HI everyone,
I'm performing the same simulation (overrunning of the turbine).
I'm calculating the rotating velocity at the previous time step as:

LIBRARY:
CEL:
&replace EXPRESSIONS:
Gamma = 9806 [N/m^3]
Raggio = 0.0454845 [m]
Torcente = torque_x()@gir_wall
deOmega = omegapunto * dt
dt = 0.002083333333333333333333333333333 [s]
grav = 9.806 [m/s^2]
inerzia = 0.00167941 [kg*m^2]
omegapunto = Torcente/inerzia
omegauno = deOmega + omegazero
omegazero = areaAve(rotvel)@gir_wall / Raggio
rho = Gamma/grav
END
END
END


I also added "rotvel" to the dependancies list in RULES file.

The error I get is:

Details of error:-
----------------
Error detected by routine PEEKL
CDANAM = /FLOW/PHYSICS/ZN2 /LIMSOLID
CRESLT = NONE

Current Directory : /FLOW/CEL/CBCK_CALLS

+================================================= ===================+
| ****** PROBLEM REPORT ****** |
|--------------------------------------------------------------------|
| Subsystem: Input |
| Subroutine name: ErrAction |
| Severity level: Fatal Error |
| Error message number: 001100279 |
|--------------------------------------------------------------------|
| Message: |
| |
| Stopped in routine MEMERR |
| |
| |
| |
| |
| |
+================================================= ===================+


What's wrong?
How can I workaround? I've also tried with a fortran user routine, but CFX returns me the same MEMERR.
pingub is offline   Reply With Quote

Old   July 15, 2011, 04:47
Default
  #6
New Member
 
Join Date: May 2010
Posts: 9
Rep Power: 16
pingub is on a distinguished road
Any advice?
pingub is offline   Reply With Quote

Old   July 15, 2011, 07:28
Default
  #7
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Isn't it obvious? rotvel is not available for callbacks (ie areaAve function), and you tried to add it in the VARIABLES files but funnily enough the solver cannot find it.

If you read the second half of stumpy's post he suggests how to work around this.
ghorrocks is offline   Reply With Quote

Old   July 15, 2011, 08:41
Default
  #8
New Member
 
Join Date: May 2010
Posts: 9
Rep Power: 16
pingub is on a distinguished road
Thanks for your answer.

I'm sorry, but I also tried to avoid the use of rotvel, I made an attempt with a constant value of omegazero. But I had problem also with the torque_x.

It seems I cannot relate the Angular Velocity to any variable but the time...

I'm trying with the stumpy's workaround, I will acknowledge you!
If you have any other ideas, please post!!!!
pingub is offline   Reply With Quote

Old   July 15, 2011, 09:58
Default
  #9
New Member
 
Join Date: May 2010
Posts: 9
Rep Power: 16
pingub is on a distinguished road
Ok, the workaround with algebraic additional variable also does'nt work.
I also tried to use Velocity w instead of rotvel, but the problem is that I cannot relate Angular Velocity to any variables but the time.

Furthermore, if I use rotvel to calculate the INLET condition (or OUTLET, or anything else), it perfectly works. The only problem is with Angular Velocity!!


My only idea is to manage it manually, step by step (PRE-SOLVER-POST-PRE-SOLVER-POST...). I only miss a slave...

I wonder how siardica did...
pingub is offline   Reply With Quote

Old   May 4, 2013, 12:31
Unhappy Angular velocity depend on Additional variable
  #10
New Member
 
hos
Join Date: May 2013
Posts: 5
Rep Power: 13
hos747 is on a distinguished road
Hi all,

I have similar error in my simulation:
I need a Angular velocity which is function of an additional variable(myspeed).

As mentioned hear, I tried to change dependency list in Rules file. but there are many Angular velocity in this file. I tried to change each of them and add A.V (myspeed).

but I faced again error:

| ERROR #001100279 has occurred in subroutine ErrAction. |
| Message: |
| Angular velocity can depend only on time for transient simulation- |
| s.


Has anybody got an idea how to edit rules file for angular velocity?

Thanks in adavance.
hos747 is offline   Reply With Quote

Old   May 5, 2013, 08:47
Default
  #11
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
stumpy's post above describes how to get around this. There is no need to edit the rules file.
ghorrocks is offline   Reply With Quote

Old   May 5, 2013, 09:53
Default
  #12
New Member
 
hos
Join Date: May 2013
Posts: 5
Rep Power: 13
hos747 is on a distinguished road
Thank you for your comment

As stumpy mentioned I have to change dependency list for angular velocity.

I have no idea how do that.
since, several times I tried edit rules file, but again crushed.

could you please explain me how I must change dependency list
hos747 is offline   Reply With Quote

Old   May 5, 2013, 17:43
Default
  #13
New Member
 
hos
Join Date: May 2013
Posts: 5
Rep Power: 13
hos747 is on a distinguished road
no one help me?
hos747 is offline   Reply With Quote

Old   May 5, 2013, 19:51
Default
  #14
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Have you read stumpy's post #2? He describes the work around there.
ghorrocks is offline   Reply With Quote

Old   May 5, 2013, 21:01
Default
  #15
New Member
 
hos
Join Date: May 2013
Posts: 5
Rep Power: 13
hos747 is on a distinguished road
yes, I have read.
but I dont know how I must edit dependency list in rules file as stumpy mentioned "Now you could try editing this file to comment out the dependency list"

please guide me

hos747
hos747 is offline   Reply With Quote

Old   May 5, 2013, 21:04
Default
  #16
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Here is a direct quote of the comment:

Quote:
The work around is probably to make an algebraic additional variable equal to probe(u)@omegaPt, then make the Angular Velocity a fn of the AV.
Have you tried this?
ghorrocks is offline   Reply With Quote

Old   May 5, 2013, 21:29
Default
  #17
New Member
 
hos
Join Date: May 2013
Posts: 5
Rep Power: 13
hos747 is on a distinguished road
yes, I have made an additional variable and then made it function of additional variable. but it crushed

error: Angular velocity can depend only on time for transient simulation
hos747 is offline   Reply With Quote

Old   May 29, 2013, 10:08
Default
  #18
New Member
 
w-idiot
Join Date: May 2013
Posts: 8
Rep Power: 0
w-idiot is on a distinguished road
Quote:
Originally Posted by hos747 View Post
yes, I have made an additional variable and then made it function of additional variable. but it crushed

error: Angular velocity can depend only on time for transient simulation
I also have similar error in my simulation!!!I know nothing to deal with it
w-idiot is offline   Reply With Quote

Old   May 29, 2013, 20:03
Default
  #19
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,870
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Have you read this thread? It explains what is going on in detail.
ghorrocks is offline   Reply With Quote

Old   May 30, 2013, 00:53
Default
  #20
New Member
 
w-idiot
Join Date: May 2013
Posts: 8
Rep Power: 0
w-idiot is on a distinguished road
Quote:
Originally Posted by ghorrocks View Post
Have you read this thread? It explains what is going on in detail.
It doesn't work! Maybe I did something wrong.Thanks!
w-idiot is offline   Reply With Quote

Reply

Tags
angular velocity, cfx-pre, probe function


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 14:20.