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April 8, 2013, 01:19 |
how to use dimensionless argument?
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#1 |
New Member
DongGunKo
Join Date: Apr 2013
Posts: 13
Rep Power: 12 |
i made UDF with argument as mass fraction
but i don't know how to use that. i have to type the argument unit but mass fraction does not have unit plz help me |
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April 8, 2013, 03:08 |
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#2 |
Senior Member
Lance
Join Date: Mar 2009
Posts: 669
Rep Power: 22 |
Do you mean in a CEL expression? You can always make your CEL expression dimensionless by dividing by the proper unit, e.g. 10 [kg]/1[kg] would result in 10 (unitless).
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April 8, 2013, 03:44 |
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#3 |
New Member
DongGunKo
Join Date: Apr 2013
Posts: 13
Rep Power: 12 |
i mean that in a user function tab, there are spaces for argument unit and result unit, but my User defined Function has a argument as a mass fraction so it is dimensionless.
typing like a m*m^-1 or something else show error in applying UDF in SOURCE TERM like below The variable 'Mass Fraction' referenced in parameter 'Source' in object '/FLOW:Flow Analysis 1/DOMAIN:R1/SUBDOMAIN:Subdomain 1/FLUID:h2ol/SOURCES/EQUATION SOURCE:continuity' does not have one of the required prefixes: component or particle component. |
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April 8, 2013, 08:51 |
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#4 |
Senior Member
OJ
Join Date: Apr 2012
Location: United Kindom
Posts: 473
Rep Power: 19 |
If you have defined the variable, using an expression that contains the main variables in CFX, you don't need to specify unit. But if you are using actual values, you need to specify units -say 1 [m s-1] etc.
In case if the variable doesn't have units, don't give it even when you use it as a value. CFX will shout only when there is a discrepancy with dimensions of both sides of the expression. OJ |
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argument, udf and programming |
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