Setting Initial Conditions and Reference Values

The direction and magnitude of the gravity vector is set via the Reference Values node. In this case, a gravity force needs to be applied in the positive x-direction.

Select the Injector > Reference Values > Gravity node.

In the Properties window, set the Value property to 9.81,0.

The initial condition for the spatial distribution of the two fluids in the continuum is that we only have glycerine in the left-hand chamber and only air in the right-hand chamber and channel. A convenient way of specifying such a distribution is by creating and using a field function.

Select the Initial Conditions > Volume Fraction node.

In the Properties window, change the Method property to Composite.

Select the Composite > C3H8O3 node and change its Method property to Field Function.

Open the Tools node at the bottom of the tree.

Right-click on the Field Functions node and select New.

Right-click on the User Field Function 1 node and rename it Initial Distribution.

In the Properties window, change the Function Name to Initial Distribution.

Click on the Definition box to open the custom editor. In the editor window, enter the following syntax:

($$Position[0] >= -0.001) ? 0 : 1

Click OK to exit the editor.

Return to the C3H8O3 node, open it and select the Field Function node beneath it

Select Initial Distribution as the Scalar Function property.

It is not necessary to specify a similar distribution for the Air node because any user-specified initial condition for the volume fraction of the last-defined phase in multiphase flows is always ignored. Instead, this condition is obtained by subtracting the sum of the volume fraction distributions of the other phases from 1.0.