Step 5: Boundary Conditions

Boundary Conditions

  Dynamic mesh motion and all related parameters are specified using the items in the Dynamic Mesh task page, not through the Boundary Conditions task page. You will set these conditions in a later step.

1.   Set the conditions for the mass flow inlet ( inlet).

Boundary Conditions inlet

  Since the inlet boundary is assigned to a wall boundary type in the original mesh, you will need to explicitly assign the inlet boundary to a mass flow inlet boundary type in ANSYS FLUENT.

(a)   Select mass-flow-inlet from the Type drop-down list in the Boundary Conditions task page.

(b)   Click Yes when ANSYS FLUENT asks you if you want to change the zone type.

  The Mass-Flow Inlet boundary condition dialog box will open.

i.   Enter 0.0116 kg/s for Mass Flow Rate.

ii.   Select Normal to Boundary from the Direction Specification Method drop-down list.

iii.   Select Intensity and Hydraulic Diameter from the Specification Method drop-down list in the Turbulence group box.

iv.   Retain 10 % for Turbulent Intensity.

v.   Enter 20 mm for the Hydraulic Diameter.

vi.   Click OK to close the Mass-Flow Inlet dialog box.

2.   Set the conditions for the exit boundary ( outlet).

Boundary Conditions outlet

   Since the outlet boundary is assigned to a wall boundary type in the original mesh, you will need to explicitly assign the outlet boundary to a pressure outlet boundary type in ANSYS FLUENT.

(a)   Select pressure-outlet from the Type drop-down list in the Boundary Conditions task page.

(b)   Click Yes when ANSYS FLUENT asks you if you want to change the zone type.

  The Pressure Outlet boundary condition dialog box will open.

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

ii.   Select Intensity and Hydraulic Diameter from the Specification Method drop-down list in the Turbulence group box.

iii.   Retain 10 % for Turbulent Intensity.

iv.   Enter 50 mm for Backflow Hydraulic Diameter.

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

3.   Set the boundary type to axis for both the axis-inlet and the axis-move boundaries.

Boundary Conditions

  Since the axis-inlet and the axis-move boundaries are assigned to a wall boundary type in the original mesh, you will need to explicitly assign these boundaries to an axis boundary type in ANSYS FLUENT.

(a)   Select axis-inlet from the Zone list and select axis from the Type list.

(b)   Click Yes when ANSYS FLUENT asks you if you want to change the zone type.

(c)   Retain the default Zone Name in the Axis dialog box and click OK to close the Axis dialog box.

(d)   Select axis-move from the Zone list and select axis from the Type list.

(e)   Click Yes when ANSYS FLUENT asks you if you want to change the zone type.

(f)   Retain the default Zone Name in the Axis dialog box and click OK to close the Axis dialog box.