Step 5: Boundary Conditions

Boundary Conditions

1.   Set the boundary conditions for the inner air stream ( central_air).

Boundary Conditions central_air Edit...

(a)   Enter 9.167e-5 kg/s for Mass Flow Rate.

(b)   Enter 0 for both X-Component of Flow Direction and Y-Component of Flow Direction.

(c)   Enter 1 for Z-Component of Flow Direction.

(d)   Select Intensity and Hydraulic Diameter from the Specification Method drop-down list.

(e)   Retain the default value of 10 for Turbulent Intensity.

(f)   Enter 0.0037 m for Hydraulic Diameter.

(g)   Click the Thermal tab and enter 293 K for Total Temperature.

(h)   Click the Species tab and enter 0.23 for o2 in the Species Mass Fractions group box.

(i)   Click OK to close the Mass-Flow Inlet dialog box.

2.   Set the boundary conditions for the air stream surrounding the atomizer
( co-flow-air).

Boundary Conditions co-flow-air Edit...

(a)   Enter 1 m/s for Velocity Magnitude.

(b)   Select Intensity and Hydraulic Diameter from the Specification Method drop-down list.

(c)   Enter 5 for Turbulent Intensity.

(d)   Enter 0.0726 m for Hydraulic Diameter.

(e)   Click the Thermal tab and enter 293 K for Temperature.

(f)   Click the Species tab and enter 0.23 for o2 in the Species Mass Fractions group box.

(g)   Click OK to close the Velocity Inlet dialog box.

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

Boundary Conditions outlet Edit...

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

(b)   Select Intensity and Viscosity Ratio from the Specification Method drop-down list.

(c)   Enter 5 for both Backflow Turbulent Intensity and Backflow Turbulent Viscosity Ratio.

(d)   Click the Thermal tab and enter 293 K for Backflow Total Temperature.

(e)   Click the Species tab and enter 0.23 for o2 in the Species Mass Fractions group box.

(f)   Click OK to close the Pressure Outlet dialog box.

4.   Set the boundary conditions for the swirling annular stream ( swirling_air).

Boundary Conditions swirling_air Edit...

(a)   Select Magnitude and Direction from the Velocity Specification Method drop-down list.

(b)   Enter 19 m/s for Velocity Magnitude.

(c)   Select Cylindrical (Radial, Tangential, Axial) from the Coordinate System drop-down list.

(d)   Enter 0 for Radial-Component of Flow Direction.

(e)   Enter 0.7071 for both Tangential-Component of Flow Direction and Axial-Component of Flow Direction.

(f)   Select Intensity and Hydraulic Diameter from the Specification Method drop-down list.

(g)   Enter 5 for Turbulent Intensity.

(h)   Enter 0.0043 m for Hydraulic Diameter.

(i)   Click the Thermal tab and enter 293 K for Temperature.

(j)   Click the Species tab and enter 0.23 for o2 in the Species Mass Fractions group box.

(k)   Click OK to close the Velocity Inlet dialog box.

5.   Set the boundary conditions for the outer wall of the atomizer ( outer-wall).

Boundary Conditions outer-wall Edit...

(a)   Select Specified Shear in the Shear Condition list.

(b)   Retain the default values for the remaining parameters.

(c)   Click OK to close the Wall dialog box.