The Default material database contains a single version of each material. Most are defined with variable properties.
When applying a material, specify if it is Fixed or Variable, and define the operating conditions of the scenario. The material properties at these conditions are computed, and either held constant or used initially and varied.
Many materials in the Default material database are defined with varying properties. To specify if they are constant or vary in a scenario:
(Alternatively, right click on the material in the Design Study bar, and select Edit material environment reference...)
The material condition (Fixed or Variable) is shown adjacent to the material name on the Design Study bar. This makes it easy to know if the correct variability is selected for the analysis type. Note that Fixed is the default setting.
To specify the scenario Environment settings
The scenario Environment settings affect all materials that have Use scenario environment enabled on the Material Environment dialog.
To change the Environment settings:
To change the Environment for an individual material
If materials operate at different conditions (such as two fluids in a cross-flow heat exchanger), the scenario Environment value is not sufficient to define their properties. To set the Environment conditions for an individual material:
To specify constant property, high temperature air
Autodesk Simulation CFD computes the properties at the Environment.
To use Air with a specified density
Property Initialization for Natural Convection
For natural convection analyses, property values must be allowed to vary (by selecting Variable) from the Material Environment dialog.
By default, initial fluid (air) property values are computed based on the lowest specified temperature boundary condition in the analysis. This is the desired behavior for simulating cooling of a device by natural convection.
For situations in which the device is heated by natural convection, it is better to initialize the fluid (air) properties based on the Environment temperature. To do this, enable the following flag in the Flag Manager: