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Creating Temperature Dependent Material Properties with Expression in Fluent

    • 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



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

      If you are unable to access the link, follow this forum discussion

      Thank you



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