Step 8: Boundary Conditions

Boundary Conditions

1.   Set the boundary conditions at the inlet ( inlet) for the mixture by selecting mixture from the Phase drop-down list in the Boundary Conditions task page.

Boundary Conditions inlet Edit...

  

(a)   Select udf membrane_speed from the Velocity Magnitude drop-down list.

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

2.   Set the boundary conditions at the inlet ( inlet) for the secondary phase by selecting water-liquid from the Phase drop-down list in the Boundary Conditions task page.

Boundary Conditions inlet Edit...

(a)   Click the Multiphase tab and enter 1 for the Volume Fraction.

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

3.   Set the boundary conditions at the outlet ( outlet) for the secondary phase by selecting water-liquid from the Phase drop-down list in the Boundary Conditions task page.

Boundary Conditions outlet Edit...

  

(a)   Click the Multiphase tab and retain the default setting of 0 for the Backflow Volume Fraction.

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

4.   Set the conditions at the top wall of the air chamber ( wall_no_wet) for the mixture by selecting mixture from the Phase drop-down list in the Boundary Conditions task page.

Boundary Conditions wall_no_wet Edit...

  

(a)   Enter 175 degrees for Contact Angles.

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

Note:   This angle affects the dynamics of droplet formation. You can repeat this simulation to find out how the result changes when the wall is hydrophilic (i.e., using a small contact angle, say 10 degrees).

5.   Set the conditions at the side wall of the ink chamber ( wall_wet) for the mixture.

Boundary Conditions wall_wet Edit...

  

(a)   Retain the default setting of 90 degrees for Contact Angles.

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