The ability to calculate a swirl velocity permits the use of a 2D mesh, so the calculation is simpler and more economical to run. This is especially important for problems where the enhanced wall treatment is used. The near-wall flow field is resolved through the viscous sublayer and buffer zones (that is, the first mesh point away from the wall is placed at a of the order of 1).

For details, see enhanced wall treatment in the Fluent Theory Guide.

9.4.5. Materials

For the present analysis, you will model air as an incompressible fluid with a density of 1.225 kg/ and a

dynamic viscosity of 1.7894 kg/m-s. Since these are the default values, no change is required in the

Create/Edit Materials dialog box.

1.Retain the default properties for air.

Physics → Materials → Create/Edit...

2. Click Close to close the Create/Edit Materials dialog box.

For details, see physical properties in the Fluent User's Guide.

9.4.6. Cell Zone Conditions

Set up the present problem using a rotating reference frame for the fluid. Then define the disk walls to rotate with the moving frame.

Setup → Cell Zone Conditions → fluid-7 Edit...

vk.com/club152685050Using a Single Rotating Reference| vk.com/id446425943Frame

1. Define the rotating reference frame for the fluid zone (fluid-7).

a.Enable Frame Motion.

b.Enter 71.08 rpm for Speed in the Rotational Velocity group box.

c.Click OK to close the Fluid dialog box.

9.4.7.Boundary Conditions

Setup → Boundary Conditions → velocity-inlet-2 Edit...

1. Set the following conditions at the flow inlet (velocity-inlet-2).

a.Select Components from the Velocity Specification Method drop-down list.

b.Enter 1.146 m/s for Axial-Velocity.

c.Retain the default selection of Intensity and Viscosity Ratio from the Specification Method dropdown list in the Turbulence group box.

d.Retain the default value of 5 % for Turbulent Intensity.

e.Enter 5 for Turbulent Viscosity Ratio.

vk.com/club152685050Using a Single Rotating Reference| vk.com/id446425943Frame

f. Click OK to close the Velocity Inlet dialog box.

2.Set the following conditions at the flow outlet (pressure-outlet-3).

Setup → Boundary Conditions → pressure-outlet-3 Edit...

a.Select From Neighboring Cell from the Backflow Direction Specification Method drop-down list.

b.Click OK to close the Pressure Outlet dialog box.

Note

ANSYS Fluent will use the backflow conditions only if the fluid is flowing into the computational domain through the outlet. Since backflow might occur at some point during the solution procedure, you should set reasonable backflow conditions to prevent convergence from being adversely affected.

3. Confirm that the wall boundary condition settings for the disk walls (wall-6) are as shown below.