# Solving Additional Variable in CFX?

 Register Blogs Members List Search Today's Posts Mark Forums Read

 November 17, 2005, 08:44 Solving Additional Variable in CFX? #1 Tuks Guest   Posts: n/a Hi all, I want to solve equations for three variables(P1, P2, P3) as additional variables. The equation for the variable variation with time is, DPi/Dt = (Nitotal-Gtotal*Piavg)/Vg for i=1,2,3 ----(a) WHERE Piavg = volumeAve(Pi)@Domain1 AND Vg=constant. Nitotal = volumeInt(Ni)@Domain1 AND Ni=K*(C - Piavg) Gtot = N1total + N2total + N3total. Is it possible to solve above equations (a)? Rightnow i am solving additional variable by Diffisive transport equation. with Diffisivity = 1E-10 m^2/s. and Source = RHS of eq(a). Can we use volmeAve and volumeInt over Domain in CEL? when i tried in CFX-10.0-Pre i got following error. "The function 'volumeAve' referenced in parameter 'Source' in object '/FLOW/DOMAINomain1/SUBDOMAIN:subreact/SOURCES/EQUATION SOURCE:SourceP2' has an invalid argument, 'N2total'. Only arguments that consist of a single variable name are supported by the solver." What is this error? NOTE: I am using the variable composition mixture in Domain1 Thank you in advance. Regards Tuks

 November 17, 2005, 10:34 Re: Solving Additional Variable in CFX? #2 Rui Guest   Posts: n/a Hi, Yes, you can use volumeAve and volumeInt in CEL. About the error, try this: create an additional variable (algebraic equation) for each Ni Regards, Rui

 November 17, 2005, 13:09 Re: Solving Additional Variable in CFX? #3 Rui Guest   Posts: n/a Take a look at the Documentation; Reference Material; CFX Expression Language; CEL Variables, Functions and Constants; CEL Functions; Additional CFX-Solver CEL Functions; variable (page 47 in CFX-5.7.1 Documentation)

 November 17, 2005, 15:15 Re: Solving Additional Variable in CFX? #4 Tuks Guest   Posts: n/a Hi Rui, Thanks you for suggestions, it really helped a lot. I defined the each Ni as Additional Variable (algebraic equations). It works well. The documentation suggested also helped. Now i could solve the equations. Yet to check validation with known values, but atleast solution has started quite well. Thank you again Regards Tuks

 November 18, 2005, 01:51 Re: Which one is right? #5 Tuks Guest   Posts: n/a Hi all, I am solving the reactions in single phase, the fluid in Domain is VARIABLE COMPOSITION MIXTURE (userMix). If additional variables are defined and we want to use those in CEL expressions then how we write those in expressions? Example, If N1 is additional variable. a1 = volmueAve(N1)@Domain1 OR a1 = volumeAve(userMix.N1)@Domain1. Which one is right? Because both are NOT giving any ERROR in Pre but in Post it says 'userMix.N1' doesnot exist? Thanks in advance Regards Tuks

 November 18, 2005, 10:33 Re: Which one is right? #6 opaque Guest   Posts: n/a Dear Tuks, For the ANSYS CFX solver both are correct; however, CFX-Post only understands what it is available in the results file. For your case (single phase I assume) only N1, and/or N1.Volumetric/Specific are available in the results file. If you want to use the same set of expressions in the CFX-Solver and CFX-Post, you must stick to the common syntax. That is, phase name prefixing is not needed for single phase flows since the phase name is implied. Good luck, Opaque.

 November 18, 2005, 12:40 Re: Which one is right? #7 Tuks Guest   Posts: n/a Hi Opaque, Thank you for your sugesstions. Regards Tuks

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post richard OpenFOAM Running, Solving & CFD 167 June 18, 2016 06:04 Unseen OpenFOAM Running, Solving & CFD 7 April 16, 2014 03:38 vaina74 OpenFOAM Running, Solving & CFD 3 June 8, 2010 12:30 velan OpenFOAM Running, Solving & CFD 1 October 17, 2008 05:36 liugx212 OpenFOAM Running, Solving & CFD 3 January 4, 2006 19:07

All times are GMT -4. The time now is 02:23.