I would like to compare experimental data against simulation data by loading in the experimental data into CFX-Post and plotting vectors. Is this possible? Do you have any hints on how it could be done? |
<br><br>The best way is to first do an export from CFX-Post for a plane, study the file arrangement and repeat the arrangement for the imported variables. Note, that 'Export... |
How is the Wall Adjacent Temperature or near wall temperature calculated (Tnw) in ANSYS CFX? |
<br><br>The answer depends upon whether the flow is laminar or turbulent. In any case, the near wall temperature is definitely not just the temperature at the first node off the... |
The Taylor impact problem from the ANSYS LS-DYNA 7.1 seminar works through release 10.0, but in 11.0, it immediately crashes. Is this a known error? |
Defect 59598 was filed and LSTC was notified of the change in behavior. However, LSTC just noted to change the hourglass control from the stiffness form to the viscous form, and the problem would... |
A user runs a thermal transient analysis in Workbench Simulation. The temperatures from each time step need to be used in a corresponding Flexible Dynamic analysis (i.e., transient structural analysis). Using the "Thermal Condition" load to read in temperatures from 100 Steps is cumbersome. Is there an easier way to accomplish this? |
A "Commands" object using the LREAD command can be used to perform such an analysis. The overall steps are outlined below:<br><br>(1) Set up and solve the Thermal... |
How do I use the FET preprocessor to TAS? |
The Adobe PDF file, FETPreprocessorUsersGuide.pdf, attached to this solution describes how to use the FET preprocessor to... |
Do you have an example demonstrating the procedure used to implement the conventional velocity effects feature for SOLID97? |
The torque on a spinning conductive disk (see attachment) can be evaluated in two ways:<br><br>(1) T = r X F (F = disk element centroidal Lorentz force, r = centroidal position... |
Is ANSYS CFX is available/supported on Mac OS X High Performance Cluster? |
There are no immediate plans to support Mac OS.
|
How can I change the Logo that appears in the Simulation Report? |
Note: This solution applies to v11 and greater. Adjust path accordingly.<br><br>1. Copy your custom logo to the following directory:<br><br>C:Program FilesANSYS... |
I am running a free surface simulation with surface tension of a bubble forming and detaching from an orifice.
If I run my case in CFX 11.0 in parallel and the bubble grows to the point where its boundaries cross parallel partition boundaries, I am seeing an unphysical increase in surface tension at the partition boundaries.
This did not happen in 10.0. What's going on? |
<br><br>Some changes were made in CFX 11.0, including a two-pass approach for calculating gradients (which are used to calculation surface tension curvature) to avoid zone-based... |
I am using ANSYS Workbench 11.0 and would like to import a pressure load from a Fluent results file just as I am able to do for CFX. Can this be done? |
<br><br>This is possible and the approach is very similar to how you would import a pressure load from CFX.<br><br>There are a couple of things you should do first,... |
CFX-Mesh V 11.0 is failing with the error: unequal number of points on periodic edges
Periodicity is not set up, and the error is highlighting the edge of a solid within a part. I have tried different mesh sizing on the adjacent parts, but nothing seems to help.
What can I do to fix this? |
<br><br>The periodicity error in this case refers to the fact that the "form one part" option in Design Modeler enforces a 1:1 mesh connection between solids within that... |
QUESTION:
A PLANE223 piezoelectric model that ran successfully at release 10 no longer runs at release 11. I now get the following error message:
*** ERROR *** CP = 187.844 TIME= 12:20:09
There are elements with negative and positive electric charge reaction
solutions for the VOLT degree of freedom inthe model. This analysis
is not valid.
Why is this happening?
ANSWER:
Your model has two components - a pair of electrodes and the piezoelectric substrate atop which they reside. Both the electrodes and piezoelectric substrate are modeled with PLANE223, keyoption(1)=1001.
There is a new feature for PLANE223 at v11 ' electroelastic coupling (useful for the simulation of electrostatically actuated MEMS devices). This is now the default behavior for PLANE223 when keyopt(1)=1001 AND when no piezoelectric properties are defined [TB,PIEZ]. For this option, the element nodal electric reaction (or 'through variable' if you prefer) is positive charge (see table 223.2 in the V11 Elements Reference). The electrodes in your model were defined in this manner.
If you define a piezo matrix [TB,PIEZ], this option of PLANE223 becomes piezoelectric and has negative electriccharge as its nodal electric reaction. This is the option you used to define the piezoelectric substrate in your model.
The conflicting reaction variables make the results that would be obtained from this combination of element types meaningless, hence the error trap. |
QUESTION:<br><br>A PLANE223 piezoelectric model that ran successfully at release 10 no longer runs at release 11. I now get the following error message:<br><br>*** ERROR... |
Class 3 Error
SYMPTOM:
The quantity of an Additional Variable is monitored during a solver run using the integrated quantity function volumeInt(<var>)@Location. This value was compared with the result of the same expression in CFX Post. On 32bit systems, the values are comparable to within a small tolerance. However, the value is very different when evaluated in the 64 bit version of CFX-Post.
PROBLEM:
This is due to a bug |
WORKAROUND:<br>No workaround is currently available.<br><br>FIXED IN:<br>ANSYS CFX Release 11.0 Service Pack 1.
|
Class 3 Error
SYMPTOM:
Transient calculations that include transported Additional Variables through porous domains do not give the correct solution for the Additional Variable. Typically in regions of porosity, the Additional Variable values are not affected by flow acceleration/deceleration due to the volume restriction.
PROBLEM:
This is due to a bug in the CFX Solver. The transient term in the transport equation for Additional Variables does not include the effect |
WORKAROUND:<br>No workaround is currently available.<br><br>FIXED IN:<br>ANSYS CFX Release 11.0 Service Pack 1.
|
Question: How to perform Single Point Response Spectrum analysis on model with superelement
Answer: The following commands will perform the spectrum analysis and combine results for the superelement and the rest of the model onto a single rst file.
FINISH
/CLEAR
!
! PARAMETER NUMMODE - MAX NUMBER OF MODES
!
NUMMODE=10 ! NUMBER OF MODES TO EXPAND
*SET,MODEDATA
*DIM,MODEDATA,,NUMMODE,4 ! LOAD STEP, ITERATION, FREQUENCY, MODE COEF
!
! GENERATE TUNNING FORK ON BEAM MODEL
!
/FILNAM,TUNNINGFORK
/PREP7
ET,1,45
ET,2,45
!
EX,1,30E6
DENS,1,0.289/386.4
NUXY,1,.3
!
K,1,0
K,2,5.5
K,3,6.5
K,4,12
KGEN,2,1,4,1,,1
KGEN,2,6,7,1,,4
KGEN,2,9,10,1,,1
K,13,KX(11),KY(11)+2
K,14,KX(12),KY(12)+2
K,15,KX(13)-3,KY(13)
K,16,KX(13)-2,KY(13)
KGEN,2,15,16,1,,4
K,19,KX(14)+2,KY(13)
K,20,KX(14)+3,KY(13)
KGEN,2,19,20,1,,4
!
LARC,10,20,14,3
LARC,12,19,14,2
LARC,15,9,13,3
LARC,16,11,13,2
!
A,1,2,6,5
A,2,3,7,6
A,3,4,8,7
VEXT,ALL,,,0,0,1
VATT,1,1,1
ASEL,NONE
VSEL,NONE
A,6,7,10,9
A,9,10,12,11
A,9,11,16,15
A,15,16,18,17
A,10,20,19,12
A,19,20,22,21
VEXT,ALL,,,0,0,1
VATT,1,1,2
ALLSEL
ESIZE,.25
NUMMRG,KP
VMESH,ALL
!
! APPLY BOUNDARY CONSTRAINTS - SIMPLY SUPPORTED BEAM
!
KSEL,,KP,,1,23,22
DK,ALL,UX
KSEL,A,KP,,4,29,25
DK,ALL,UY
DK,ALL,UZ
ALLSEL
FINISH
!
! SUPERELEMENT GENERATION PASS
!
!
/SOLUTION
ANTYPE,SUBST
EMATWRITE,YES ! FORCE WRITTING OF EMAT - NEEDED FOR EXPANSION PASS
SEOPT,TUNNINGFORK,2
CMSOPT,FIX,NUMMODE ! COMPONENT MODE SYNTHESIS OPTIONS - 10 MODES
!
! WE ARE USING COMPONENT MODE SYNTHESIS METHOD FOR SUPERELEMENT
! TO RETAIN THE DYNAMIC BEHAVIOR OF THE TUNNING FORK
!
! SET MASTER DEGREES OF FREEDOM AT INTERFACE
!
ASEL,,AREA,,12 ! INTERFACE BETWEEN MODEL AND SUPERELEMENT
NSLA,,1
M,ALL,ALL
!
! SELECT TUNNING FORK ONLY
!
ESEL,,TYPE,,2
NELEM
SOLVE
FINISH
SAVE
!
! MODAL ANALYSIS - USE PASS
!
/CLEAR
RESU,TUNNINGFORK,DB
/FILNAM,USEPASS
/PREP7
ALLSEL
ET,3,MATRIX50
ESEL,,TYPE,,1
NELEM
TYPE,3
SETRAN,TUNNINGFORK
SE,TUNNINGFORK
FINISH
!
/SOLUTION
ANTYPE,MODAL
MODOPT,LA |
Question: How to perform Single Point Response Spectrum analysis on model with superelement<br><br>Answer: The following commands will perform the spectrum analysis and combine results... |
Class 3 Error
SYMPTOM:
When running a free surface bubble simulation with surface tension enabled, if the case is run in parallel and the bubble boundary crosses any parallel partition boundaries, an unphysical increase in surface tension at the partition boundaries is observed.
This problem does not occur in ANSYS CFX 10.0.
PROBLEM:
This is due to a bug in the CFX Solver. The expert parameter 'element surface tension force' controls curvature interpolation as well as how the interface delta function is calculated. In ANSYS CFX 11.0, this is calculated from control volume gradients of volume fraction. Because of the bug, the interface delta function used to calculate the surface tension force used in Rhie Chow redistribution at partition boundaries i |
WORKAROUND:<br>Set the expert parameter 'element surface tension force' to 't' to revert to ANSYS CFX 10.0 behaviour.<br><br>FIXED IN:<br>ANSYS CFX Release 11.0 Service Pack... |
QUESTION: Do you have a brake squeal model solved in WB v11? I imagine command snippets will be required to access the QRDAMP eigensolver.
ANSWER: An example supplied by one of our developers is attached to this solution |
QUESTION: Do you have a brake squeal model solved in WB v11? I imagine command snippets will be required to access the QRDAMP eigensolver.<br><br>ANSWER: An example supplied by one of... |
Class 3 Error
SYMPTOM:
In the DOMAIN editor in CFX-Pre, if the reference pressure value is deleted, either by deleting the number in the value-units editor, or by switching to expression mode and setting a blank expression, the Reference Pressure will silently be set to its default (1 [atm] at present). In other words, this value is not displayed on the form but, if the form is committed, the default value is committed for the parameter.
PROBLEM:
This is due to a bug in the CF |
WORKAROUND:<br>Ensure that a value or expression is explicitly set for the Reference Pressure.<br><br>FIXED IN:<br>ANSYS CFX Release 11.0 Service Pack 1.
|
Class 3 Error
SYMPTOM:
Incorrect answers are obtained when calculating multiphase flows with heat transfer, either homogeneous or inhomogeneous, and either thermal or total energy, when the turbulence model is set to be homogeneous.
PROBLEM:
This is due to a bug in the way the turbulent wall functions are calculated for heat transfer. These should use bulk quantities, and not fluid de |
WORKAROUND:<br>No workaround is currently available.<br><br>FIXED IN:<br>ANSYS CFX Release 11.0 Service Pack 1.
|
A. Can we monitor displacement and stress of user specified nodes on MFX-FSI analysis?
A. It turns out that with MFX, the NLHIST command only works for quantities defined on the interface. |
A. Can we monitor displacement and stress of user specified nodes on MFX-FSI analysis?<br><br><br>A. It turns out that with MFX, the NLHIST command only works for quantities... |
The wall roughness is not available in CFX-Post for plotting on boundaries. |
<br><br>By default the wall roughness is not output to the results file. By adding some simple command language (CCL), wall roughness can be included and should then be available as... |
When opening a simulation in CFX-Pre or CFX-Post, the following error message is encountered:
Syntax error: load parameters should have the format: param=value |
<br><br>This error message is caused by the presence of one or more commas in the name of the file being opened or in the directory in which the file resides. The solution is to check... |
How do you apply a temperature gradient to a BEAM18x element? |
In ANSYS Release 11.0 BEAM18x elements, temperatures are input as element body loads at three locations at each end node of the beam. The temperatures are input using the VAL1, VAL2, and VAL3... |
How do I set the pressure profile at a vertical pressure boundary for free surface flow? |
<br>In CFX it is possible to set a buoyancy reference density which causes the gravity head associated with this density to be removed from the pressure field. Thus, with a single,... |
I have specified the thermal phase change model for mass transfer in CFX-Pre, but the box for the saturation temperature is not appearing. |
<br>If you define a homogeneous binary mixture which contains the same materials you are using in your fluid pair the saturation temperature is defined by the binary mixture and does not... |