### 1.4.11. Library Materials

CFX-Pre provides an extensive list of library materials for which the properties have already been set. These materials can be used directly in a simulation or as a template to define customized materials with similar properties. The default materials library is stored in the `MATERIALS` file located in the `CFX/etc/` directory. You can also edit/add to the `MATERIALS` file, but this is considered an expert feature. For details, see Adding to the MATERIALS file. Exporting and Importing CCL files is a simpler way to transferring material data from one simulation to another.

The properties for many materials have been evaluated at Standard Temperature and Pressure (STP), defined as 0°C (273.15 K) and 1 atm (101325 Pa). The long name provided with most materials will indicate the condition at which constant properties were evaluated or possibly the range over which the properties apply. It is important to note that using library materials will produce inaccurate results if your simulation conditions depart significantly from those at which the material properties were evaluated.

Some pre-supplied materials have properties defined in different ways, depending on the type of modeling for which they will be used. For example, there are two material groups for “gases.” In the material group drop-down list, you will see that there is a group for constant properties and a group for Ideal Gases. All the materials in the first group have both constant density and constant specific heat capacity. All materials in the second group use the Ideal Gas equation of state but have constant specific heat capacity.

In particular, Air at STP and Air Ideal Gas are two examples. In addition, a third material such as Air at 25 C is also available if Air at STP is not appropriate. The last version of `Air` uses material properties evaluated at 25 C instead of 0 C. You should select the appropriate material for your simulation; this may require you to modify the properties of an existing material or create a new material.

To view the properties of the template materials, you can select it in the tree view and then click the Edit icon. The Materials details view will open and you will be able to see the material properties.

#### 1.4.11.1. Adding to the MATERIALS file

If you frequently use a material that is not defined in the `MATERIALS` file, you may want to add it to the main `MATERIALS` file. Using a text editor, you can access the file

`CFX/etc/MATERIALS` and make any necessary revisions.

Note: You should make a local copy of the `MATERIALS` file and rename it so that the backup database can be restored at a later date. Your changes should then be made to copy named `MATERIALS`.

To enable CFX-Pre to correctly read your new material, the format should exactly match that of existing materials. Therefore, you should use one of the existing materials as a template for entering the properties of your material.

The best way to do this is to create your new material in CFX-Pre, write the material to a file using File > Export > CCL, and then cut and paste the material from that file into your local copy of the materials file.

Release 18.2 - © ANSYS, Inc. All rights reserved.