Defining an Analytic Function
Assume that you want to define the density ρ1 for a material as a function of pressure and temperature: ρ1= ρ1(p, T). You can name the function rho1(p,T) and use the expression p*0.02897/8.314/T to define the function.
1
In the Materials toolbar, click the Browse Materials , Add Material , or Blank Material button to add a new material to the Component (or use an existing material where density is not defined, or redefine the current expression for the density).
2
Add a Density property to the material.
a
In the Model Builder, click the Material node.
b
In the Settings window for Material, click to expand the Material Properties section. Under Basic Properties, right-click Density and Add to Material.
A Density property is added to the Basic property group.
3
In the Model Builder, under the material node, right-click Basic and select Functions > Analytic. This adds an Analytic subnode () under Basic.
4
In the Settings window for Analytic, enter rho1 in Function name. Replace the default name.
5
Under the Definition section:
a
In the Expression field, enter p*0.02897/8.314/T.
b
In the Arguments column, enter p,T.
6
Under Units:
a
In the Arguments field, enter Pa, K as the units for the pressure and the temperature, respectively.
b
In the Function field, enter kg/m^3 as the unit for the function’s output (density). The function rho1 can now be used to define the density in your material.
7
Click the Material node. In the Settings window for Material, under Material Contents, enter rho1(p,T) in the Value column (in the Density row).
Click the Basic node to notice that the Density analytic function is defined in the Settings window for Property Group under Output Properties. The expression will be orange if there are no variables p and T for pressure and temperature, respectively, defined in the component. See Figure 2-13.
Figure 2-13: A density property is defined using an analytic function.