Defining the Cutting Blade Rotation

You define only a rotational motion for the lawnmower blade, which rotates around the y axis with 3625 rpm. The translational motion of the lawnmower is accounted for by specifying a relative tangential velocity at the bottom boundary, that is, the grass moves towards the lawnmower blade.

To define the cutting blade rotation:
  1. Create a rotational motion for the lawnmower blade:
    1. Right-click the Tools > Motions node and select New > Rotation.
    2. Select the Rotation > Rotation Axis node and set the following properties:
      Property Setting
      Direction [0.0, 1.0, 0.0]
      Origin [0.0, ${Blade Height}, 0.0]
    3. Select the Rotation > Rotation Rate node and set Rotation Rate to -3625.0 rpm.
    4. Select the Regions > Blade > Physics Value > Motion Specification node and set Motion to Rotation.
  2. To specify the boundary conditions:
    1. Select the Regions > Domain > Boundaries > Bottom > Physics Conditions node and set the following properties:
      Node Property Setting
      Lagrangian Specification Method Specify for Boundary
      Tangential Velocity Specification Method Vector
    2. Select the Bottom > Physics Values > Relative Velocity node and set Value to [-${Lawnmower Velocity}, 0.0, 0.0].
  3. Save the simulation.