Setting Up the Initial Oil Bath

For the simulation of oil bath lubrication, you describe the initial shape and position of the oil bath in the form of a geometry part that forms a closed surface. Within this geometry part, oil particles of a specified diameter are created during initialization. The size of the particles represents the discretization of the fluid. For this part of the tutorial, you use a particle diameter of 1 mm.

The following diagram displays the procedure for creating the initial domain of the oil:


You start from a block that is snapped to the gear housing and set its height to the initial height of the oil. Then, you intersect the block with the gear housing. Finally, you subtract the gear from the intersection.

Initially, the fluid is at rest with a pressure of 1 bar. Therefore, you can leave the initial conditions for velocity and pressure at their default values.

To set the initial conditions of the oil:
  1. Create the volumetric shape that describes the initial shape and position of the oil:
    1. In the Graphics window, click the Geometry Scene 1 tab.
    2. Right-click the Geometry > Parts node and select New Shape Part > Block.
      The block is automatically snapped to the gear housing.
    3. Within the Create Block Part dialog, in the Maximum and Minimum Coordinates group box, for Corner 2, set Z to -0.025 m, then click Create and Close.
    4. Multi-select the Parts > Block and housing nodes, right-click one of the selected nodes, and select Create Mesh Operation > Boolean > Intersect.
    5. In the Create Intersect Operation dialog, activate Execute Operation Upon Creation, then click OK.
    6. Select the Parts > Intersect and gear nodes, right-click one of the selected nodes, and select Create Mesh Operation > Boolean > Subtract.
    7. In the Create Subtract Operation dialog, set the following properties, then click OK:
      Property Setting
      Target Part Intersect
      Execute Operation Upon Creation Activated
    8. Rename the Parts > Subtract node to Oil Initial.
      This part describes the initial domain of the oil phase.
  2. To ensure that there are no gaps between the initial oil part and the surfaces of the gear housing and the gear, imprint the parts:
    1. Multi-select the Parts > housing, gear, and Oil Initial nodes, right-click one of the selected nodes, and select Create Mesh Operation > Boolean > Imprint.
    2. In the Create Imprint Operation dialog, click OK.
    3. Right-click the Operations > Imprint node and select Execute.
  3. To generate the oil particles within the created initial oil part, edit the Regions > gearbox > Physics Values node and set the following properties:
    Node Property Setting
    Physics Values
    Particle Base Size Value 0.001 m
    Particle Generation Parts Oil Initial
  4. Save the simulation.