Loading the Starting Simulation File

For this tutorial, you are provided with a starting simulation file that contains the geometry of the lawnmower blade inside the computational domain and pre-defined regions with boundaries. Since you are using the meshless DEM methodology for this tutorial, there is one solid region for the lawnmower blade and a particle region for the encompassing computational domain. The parameters that you use to specify several settings in the tutorial are already included on the starting simulation file.

To load the starting simulation file:
  1. Start up Simcenter STAR-CCM+ in a manner that is appropriate to your working environment and select File > Load....
  2. In the Load a File dialog:
    1. Select an appropriate Process Option.
      Both serial and parallel processes are suitable for this tutorial.
    2. Click Browse.
    3. In the Open dialog, navigate to the discreteElementMethod folder of the downloaded tutorial files and select flexibleFiber_start.sim.
    4. Click Open, and then OK.
  3. To visualize the geometry, open the Scenes > Lawnmower Scene.


  4. Expand the Automation > Parameters node and review the pre-defined parameters.
    The following table presents their definitons:
    Parameter Value Definition
    Blade Diameter 450.0 mm The diameter of the lawnmower blade's casing.
    Blade Height 74.93 mm The elevation of the lawnmower blade above the ground. This value must be smaller than the height of the grass blades.
    Domain Height ${Blade Height}*7 The height of the domain geometry. This value must be greater than the Blade Height.
    Domain Length ${Blade Diameter}*1.6 The length of the domain geometry. This value must be greater than the Blade Diameter.
    Domain Width ${Blade Diameter}*2 The width of the domain geometry. This must be greater than the Blade Diameter.
    Grass Blade Diameter 5.08 mm The grass blade segments are cylindrical; this value is the diameter of the cylinders.
    Grass Blade Height 114.3 mm This is the maximum initial height of the grass blades. This value must be greater than the Blade Height.
    Grass Blade Injection Rate 
    ceil(${Grass Blade Separation}/${Lawnmower Velocity}/${Time Step})
    		 A row of grass blades is injected every time this number of time steps is reached.
    Grass Blade Number 
    floor((${Domain Width}-${Grass Perimeter Offset}*2)/${Grass Blade Separation})+1
    		 The number of grass blades in a row of grass blades. This is the number of injection points in the injector.
    Grass Blade Segments 10.0 The number of segments in each grass blade. Each grass blade is made of 10 identical cylindrical flexible fiber segments stacked on top of each other.
    Grass Blade Separation 19.05 mm The distance between each grass blade. This parameter is used to set up the injector.
    Grass Blade Stiffness 1000000.0 N/m The spring stiffness of the grass blade fiber segments. This parameter is used to set up the multiphase interactions.
    Grass Perimeter Offset ${Domain Width}*0.1 The distance between the side walls of the domain and the point at the bottom of the domain where the grass blades are injected. This value must be at least equal to the distance between grass blades to prevent the top of the oscillating grass blades from hitting the side walls of the domain.
    Lawnmower Velocity 2.0 m/s The tangential lawnmower blade velocity for the ground boundary in the positive z direction.
    Output Time Frequency 0.001 s The post-processing of the lawnmower simulation occurs at this interval of time.
    Time Step 1.0E-4 s The time-step of the implicit solver.
  5. Save the simulation as flexibleFiber.sim.