Learning Forum

[m_gonser]

Hello together, 

i am struggling to define the dynamic viscosity of my fluid in the material properties settings in Fluent.
I received the temperature dependent density and temperature dependent kinematic viscosity of a fluid. Both are given as a polynominal function. As i cannot enter the kinematic viscosity properties of the fluid directly, i want to create a new expression for the dynamic viscosity (Density*Kinematic Viscosity)

The equation is as followed:

(A0 [kg/m^3] * StaticTemperature * StaticTemperature * 1 [K^-2]
+ A1 [kg/m^3] * StaticTemperature * 1 [K^-1]
+ A2[kg/m^3])

*(B0 [m^2*s^-1]*StaticTemperature^6*1[K^-6]
- B1[m^2*s^-1]*StaticTemperature^5*1[K^-5]
+ B2[m^2*s^-1]*StaticTemperature^4*1[K^-4]
- B3 [m^2*s^-1]*StaticTemperature^3*1[K^-3]
+ B4 [m^2*s^-1]*StaticTemperature^2*1[K^-2]
- B5 [m^2*s^-1]*StaticTemperature*1[K^-1]
+ B6[m^2*s^-1])

 

I Also tried to create a new named expression to define the kinematic vicosity with StaticTemperature as variable. But i always get the error "Expression is invalid in current model setup"

I defined the density as a polynomial function already.

I do not have a lot of experience in Fluent and hope one of you guys can help me out here.

Thank you already!

[SRP]

 

Hi,

To learn more about expressions, please check the user's guide.: 5.1. Introduction to Expressions (ansys.com)

If you are unable to access the link, follow this forum discussion /forum/forums/topic/using-help-with-links/#latest

Thank you

Saurabh