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Home Forums ANSYS Fluent Beginners to Advanced level Lesson 22: Expression

• # Lesson 22: Expression

Posted by on February 5, 2024 at 5:44 pm

How to write expression in cp as there is no option to add expression?

replied 2 months, 1 week ago 2 Members · 5 Replies
• 5 Replies
• ### Rahul

Member
February 6, 2024 at 7:39 am

Hi Bibek,

You can use the New Input Parameter option from the drop-down list to use an expression.

Regards
Rahul
Flowthermolab support

• ### Bibek

Member
February 6, 2024 at 3:18 pm

But I’m not able to use functions, variables part.

While I’m writing, it shows errors.

How to do it? Is this the right way?

• ### Rahul

Member
February 6, 2024 at 3:59 pm

Hi Bibek,
The unit/dimension of each addition term should be the same, and equal to the unit of the property, say specific heat. So if unit of Cp is J/(kgK), each term should also have that unit. When you are using a constant value in the expression, that too should be given the unit. For example, 9[kg m^-3 K^-1] corresponding to the unit of the variable.
Also, T is not a variable recognized in Fluent. When you start typing the variable name, say T, a drop down will appear with list of options, where you can select the variables (check attached pic).
Best regards
Rahul

• ### Bibek

Member
February 6, 2024 at 4:03 pm

I did try that with totaltemperature. But shows similar errors, units couldn’t match

• ### Rahul

Member
February 6, 2024 at 4:25 pm

Units you will have to try and match based on which. For example, the variable T in the shared image cannot be used. And even if you have defined T as another expression, you need to give corresponding unit to that expression. If using a constant value, use the units also as they have shown.
One thing you could try to do is define the units in terms of the basic dimensions(like kg, m, s, K etc), rather than the units.