Troubleshooting probe and average functions with Angular Velocity

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 July 28, 2009, 13:17 Troubleshooting probe and average functions with Angular Velocity #1 New Member   Join Date: Jul 2009 Posts: 4 Rep Power: 10 Sponsored Links 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?

 July 29, 2009, 07:01 #2 Senior Member   Join Date: Apr 2009 Posts: 532 Rep Power: 14 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 //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.

 July 29, 2009, 15:02 #3 New Member   Join Date: Jul 2009 Posts: 4 Rep Power: 10 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!

 July 29, 2009, 19:13 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,737 Rep Power: 106 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

 July 13, 2011, 09:26 #5 New Member   Join Date: May 2010 Posts: 9 Rep Power: 9 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.

 July 15, 2011, 03:47 #6 New Member   Join Date: May 2010 Posts: 9 Rep Power: 9 Any advice?

 July 15, 2011, 06:28 #7 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,737 Rep Power: 106 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.

 July 15, 2011, 07:41 #8 New Member   Join Date: May 2010 Posts: 9 Rep Power: 9 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!!!!

 July 15, 2011, 08:58 #9 New Member   Join Date: May 2010 Posts: 9 Rep Power: 9 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...

 May 4, 2013, 11:31 Angular velocity depend on Additional variable #10 New Member   hos Join Date: May 2013 Posts: 5 Rep Power: 6 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.

 May 5, 2013, 07:47 #11 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,737 Rep Power: 106 stumpy's post above describes how to get around this. There is no need to edit the rules file.

 May 5, 2013, 08:53 #12 New Member   hos Join Date: May 2013 Posts: 5 Rep Power: 6 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

 May 5, 2013, 16:43 #13 New Member   hos Join Date: May 2013 Posts: 5 Rep Power: 6 no one help me?

 May 5, 2013, 18:51 #14 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,737 Rep Power: 106 Have you read stumpy's post #2? He describes the work around there.

 May 5, 2013, 20:01 #15 New Member   hos Join Date: May 2013 Posts: 5 Rep Power: 6 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

May 5, 2013, 20:04
#16
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Glenn Horrocks
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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?

 May 5, 2013, 20:29 #17 New Member   hos Join Date: May 2013 Posts: 5 Rep Power: 6 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

May 29, 2013, 09:08
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w-idiot
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Quote:
 Originally Posted by hos747 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

 May 29, 2013, 19:03 #19 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,737 Rep Power: 106 Have you read this thread? It explains what is going on in detail.

May 29, 2013, 23:53
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w-idiot
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Quote:
 Originally Posted by ghorrocks Have you read this thread? It explains what is going on in detail.
It doesn't work! Maybe I did something wrong.Thanks!

 Tags angular velocity, cfx-pre, probe function

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