8.1.2 Using the Materials Task Page

The Materials task page (Figure  8.1.1) allows you to define the materials and their properties in your problem setup using either the Fluent Database or a User-Defined Database. It allows you to copy materials from a database, create new materials, and modify material properties.

These generic functions are described in this section. The inputs for temperature-dependent properties are explained in Section  8.2. The specific inputs for each material property are discussed in the remaining sections of this chapter.

Materials

Figure 8.1.1: The Materials Task Page

By default, your local materials list will include a single fluid material (air) and a single solid material (aluminum). If the fluid involved in your problem is air, you can use the default properties for air or modify the properties. If the fluid in your problem is water, you can either copy water from the ANSYS FLUENT database or create a new "water'' material from scratch. If you copy water from the database, you can still make modifications to the properties of your local copy of water. The editing or creating of material properties is done in the Create/Edit Materials dialog box. To display the Create/Edit Materials dialog box, select the Create/Edit... button in the Materials task page. See the following sections for detailed information on how to change material properties.

Mixture materials will not exist in your local list unless you have enabled species transport (see Chapter  15). Similarly, inert, droplet, and combusting particle materials will not be available unless you have created a discrete phase injection of these particle types (see Chapter  23). When a mixture material is copied from the database, all of its constituent fluid materials (species) will automatically be copied over as well.

Modifying Properties of an Existing Material

Probably, the most common operation you will perform in the Create/Edit Materials dialog box is the modification of properties for an existing material. The steps for this procedure are as follows:

1.   Select the material you want to modify and the Create/Edit... button in the Materials task page.

2.   In the Create/Edit Materials dialog box select the type of material ( fluid, solid, etc.) in the Material Type drop-down list.

3.   Choose the material for which you want to modify properties, in the Fluent Fluid Materials drop-down list, Fluent Solid Materials list, or other similarly named list. The name of the list will be the same as the material type you selected in the previous step.

4.   Make the required changes to the properties listed in the Properties section of the dialog box. You can use the scroll bar to the right of the Properties section to scroll through the listed items.

5.   Click on the Change/Create button to change the properties of the selected material to your new property settings.

To change the properties of an additional material, repeat the process described above. Click the Change/Create button after making changes to the properties for each material.

Renaming an Existing Material

Each material is identified by a name and a chemical formula (if one exists). You can change the name of a material, but not its chemical formula (unless you are creating a new material). The procedure for renaming a material is as follows:

1.   Select the material you want to rename and the Create/Edit... button in the Materials task page.

2.   In the Create/Edit Materials dialog box, choose the material for which you want to modify properties, in the Fluent Fluid Materials list, Fluent Solid Materials list, or other similarly named list. The name of the list will be the same as the material type you selected in the previous step.

3.   Enter the new name in the Name field at the top of the Create/Edit Materials dialog box.

The maximum character length you can enter in the Name field is 29. If you enter a material name that is more than 29 characters long, ANSYS FLUENT will print an error message in the console window.

4.   Click on the Change/Create button.

A Question dialog box (see Section  2.1.6) will appear, asking you if the original material should be overwritten.

If you are renaming the original material, click Yes to overwrite it. If you were creating a new material, click No to retain the original material.

To rename another material, repeat the process described above. Click the Change/Create button after renaming each material.

Copying Materials from the ANSYS FLUENT Database

The global (site-wide) materials database contains many commonly used fluid, solid, and mixture materials, with property data from several different sources [ 49, 67, 93, 34]. To use one of these materials in your problem, copy it from the ANSYS FLUENT database to your local materials list. The procedure for copying a material is as follows:

1.   Click on the Fluent Database... button in the Create/Edit Materials dialog box to open the Fluent Database Materials dialog box (Figure  8.1.2).

Figure 8.1.2: Fluent Database Materials Dialog Box

2.   Select the type of material ( fluid, solid, etc.) in the Material Type drop-down list.

3.   In the Fluent Fluid Materials list, Fluent Solid Materials list, or other similarly named list, choose the materials you wish to copy by clicking on them. The properties of the selected material will be displayed in the Properties area.

4.   To check the material properties, use the scroll bar to the right of the Properties area to scroll through the listed items. For some properties, temperature-dependent functions are available in addition to the constant values. Select one of the function types in the drop-down list to the right of the property and the relevant parameters will be displayed. You cannot edit these values, but the dialog boxes in which they are displayed function in the same way as those used for setting temperature-dependent property functions (Section  8.2).

  The inactive buttons in the Fluent Database Materials dialog box are operations that are applicable only for a user-defined database. These operations will be available when you click the User-Defined Database... button in the Create/Edit Materials dialog box.

5.   Click Copy. The materials and their properties will be downloaded from the database into your local list, and your copy of properties will now be displayed in the Materials task page.

6.   Close the Fluent Database Materials dialog box.

After copying a material from the database, you can modify its properties or change its name, as described earlier in this section. The original material in the database will not be affected by any changes made to your local copy of the material.

Creating a New Material

If the material you want to use is not available in the database, you can easily create a new material for the local list. This material will be available for use only for the current problem and will not be saved in the ANSYS FLUENT database. The procedure for creating a new material is as follows:

1.   Select the Create/Edit... button in the Materials task page.

2.   Select the new material type ( fluid, solid, etc.) in the Material Type drop-down list. It does not matter which material is selected in the Fluent Fluid Materials, Fluent Solid Materials, or other similarly named list.

3.   Enter the new material name in the Name field.

The maximum character length you can enter in the Name field is 29. If you enter a material name that is more than 29 characters long, ANSYS FLUENT will print an error message in the console window.

4.   Set the material's properties in the Properties area. If there are many properties listed, you may use the scroll bar to the right of the Properties area to scroll through the listed items.

5.   Click on the Change/Create button. A Question dialog box (see Section  2.1.6) will appear, asking you if the original material should be overwritten.

(a)   Click on No to retain the original material and add your new material to the list. A dialog box will appear asking you to enter the chemical formula of your new material.

(b)   Click OK, enter the formula if it is known. Else, leave the formula blank and click on OK. Select the Change/Create button and answer the Question.

The Materials task page will be updated to show the new material name and chemical formula in the Fluid Materials list (or Fluent Solid Materials or other similarly named list).

Saving Materials and Properties

All the materials and properties in your local list are saved in the case file when it is written. If you read this case file into a new solver session, all of your materials and properties will be available for use in the new session.

Deleting a Material

If there are materials in your local materials list that you no longer need, you can delete them:

1.   Choose the material to be deleted in the Materials task page.

2.   Click on the Delete button at the bottom of the Materials task page.

You can also delete materials in the Create/Edit Materials dialog box.

1.   Select the material to be deleted and click the Create/Edit... button in the Materials task page.

2.   In the Create/Edit Materials dialog box, select the type of material ( fluid, solid, etc.) in the Material Type drop-down list.

3.   Choose the material to be deleted in the Fluent Fluid Materials drop-down list, Fluent Solid Materials list, or other similarly named list. The list's name will be the same as the material type you selected in the previous step.

4.   Click on the Delete button at the bottom of the Materials task page.

Deleting materials from your local list will have no effect on the materials contained in the global database.

Changing the Order of the Materials List

By default, the materials in your local list and those in the database are listed alphabetically by name (e.g., air, atomic-oxygen (o), carbon-dioxide (co2)). If you prefer to list them alphabetically by chemical formula, select the Chemical Formula option under Order Materials By. The example materials listed, will now be in the order of: air, co2 (carbon-dioxide), o (atomic-oxygen). To change back to the alphabetical listing by name, choose the Name option under Order Materials By.

You may specify the ordering method separately for the Create/Edit Materials dialog box and Fluent Database Materials dialog box. For example, you can order the database materials by chemical formula and the local materials list by name. Each dialog box has its own Order Materials By options.