Viscosity as a function of coordinates
Viscosity as a function of coordinates
(OP)
Hi!
I am trying to define a fluid in ANSYS-CFD whith a viscosity as a function of the x-coordinate. Is there anybody who can tell me, what I am doing wrong? :
*dim, visctab, table, 2, 1, 1, x
visctab(1,0)=0 ! 1st x-coordinate
visctab(2,0)=1.5 ! 2nd x-coordinate
visctab(1,1)=80e-6 ! Viscosity at the 1st x-coordinate
visctab(2,1)=20e-6 ! Viscosity at the 2nd x-coordinate
flda,prot,visc, %visctab%
Then I get these error message:
"Specified fluid not found in property database. Use FLDA,prot to reselect a valid fluid type, or add the desired fluid to the fluid property database manually. VISCTAB."
Thank you very much!
I am trying to define a fluid in ANSYS-CFD whith a viscosity as a function of the x-coordinate. Is there anybody who can tell me, what I am doing wrong? :
*dim, visctab, table, 2, 1, 1, x
visctab(1,0)=0 ! 1st x-coordinate
visctab(2,0)=1.5 ! 2nd x-coordinate
visctab(1,1)=80e-6 ! Viscosity at the 1st x-coordinate
visctab(2,1)=20e-6 ! Viscosity at the 2nd x-coordinate
flda,prot,visc, %visctab%
Then I get these error message:
"Specified fluid not found in property database. Use FLDA,prot to reselect a valid fluid type, or add the desired fluid to the fluid property database manually. VISCTAB."
Thank you very much!





RE: Viscosity as a function of coordinates
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RE: Viscosity as a function of coordinates
"... if your fluid properties can be expressed as a table, you can enter a table name. To enter a table name, you must first define a TABLE type array parameter using the *DIM command. Note that you must enclose the table name in
% symbols in the FLDATA7 command line (e.g., FLDATA7,PROT,DENS,%tabname%). "
RE: Viscosity as a function of coordinates
You don't have a problem with the "being able to specify as a table" bit. However, the problem you have is how to associate this so-called x-coordinate to your model viscosity using this method. How do you intend to do that? The implied statement in the above is "a function of TIME i.e.
"...if your fluid properties can be expressed as a table (as a function of TIME), you can enter a table name."
Otherwise, how will ANSYS know that you require viscosity to be a function of an "x-coordinate"? It won't.
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RE: Viscosity as a function of coordinates
Thank you for your reply!
I thought, by defining as primary variable the x-variable it will know:
*dim, visctab, table, 2, 1, 1, x
hier a pargraph from ansys manual:
"
9.2.6.1. Using a Fluid Property Table
If working interactively, you define a new table prior to using the table to apply loads. You can define a table interactively via the Utility Menu> Parameters> Array Parameters> Define/Edit menu path, or in batch mode via the *DIM command. If working interactively, you will be asked to define the table through a series of dialog boxes. If working in batch mode, you need to define the table before issuing any of the loading commands.
When you define the table, you can define the following primary variables:
Temperature (TEMP)
Pressure (PRESSURE)
Time (TIME)
X-coordinate (X)
Y-coordinate (Y)
Z-coordinate (Z)
Velocity (VELOCITY)
Reference X-coordinate (Xr) (ALE formulation only)
Reference Y-coordinate (Yr) (ALE formulation only)
Reference Z-coordinate (Zr) (ALE formulation only)
"
Regards
Alex
RE: Viscosity as a function of coordinates
Take a look at:
Theory Reference> Chapter 7. Fluid Flow>
7.6. Fluid Properties> 7.6.2. Viscosity
...
...
Table: For the table type, you enter viscosity data as a function of temperature (using the MPTEMP and MPDATA commands).
The above is, I know, the TABLE parameter in the fldat command. But there is nothing else mentioned regarding the use of viscosity as a function of...(anything other than temperature).
However, doing a search on Google brought up several hits on viscosity as a function of... (something), which all pointed to an ANSYS UPF. See:
Advanced Analysis Techniques Guide> Chapter 12. User-Programmable Features and Nonstandard Uses >
and scroll down to "User Viscosity".
Also, do a search in the ANSYS help for UserVisLaw or go to fldata7 in the help and scroll down to:
Hope this helps, not sure how much more I can extract from the help file.
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See FAQ569-1083 for details on how to make best use of Eng-Tips.com
RE: Viscosity as a function of coordinates