Static Angle of Repose using Ansys Rocky

Hi everyone, and welcome to this tutorial. Today, we will simulate a static repose angle test in Ansys Rocky. We will obtain the angle by both manual and automatic methods. Let's get started!

Project Setup

1. Click on the New Project icon and save it accordingly.
2. In the Study section, write notes involving the setup of your model.

Physics Configuration

• Ensure that Gravity is enabled and change the option as shown.
• Include the adhesive force and the rolling resistance model.

Geometry Import

1. Import the geometry files in STL format from the folder and select millimeters as the import unit.
2. Drag and drop both geometries into the workspace to visualize them.
3. Use the mouse to rotate, pan, and zoom in and out.

Motion and Material Properties

• The cylinder moves vertically upwards. The translation motion is the default option.
• Define the range of time, velocity, and its direction. Preview the motion before running the simulation.
• Modify the material properties as desired. Note that in this model, we only have particles and boundaries.

Material Interactions

Specify different data for material interactions. One of them is the parameter named Force Fraction, required for the constant adhesive force model. This force is equal to the gravity force multiplied by the force fraction.

Particle Size and Shape

• Define the particle size and shape. We will use spheres, but you can select a different option.
• The rolling resistance is a parameter related to the concept of rolling resistance moment, based on the full mobilization rolling angle. Set up this value accordingly.

Particle Visualization

Visualize the particle by clicking on View. We must use a volumetric inlet. Here's why:

• The cylinder moves vertically upwards, and the particles are released.
• If we use a particle inlet option, we will see separated particles, which don't fully fill the space.

Seed Point Definition

1. Define the seed point, from which an amount of particles will be created. Four parameters are required in the setup:
2. Select the particle we created before and set the target mass.
3. The gap factor is 1 by default.
4. Set the boundaries and the coaxial mass.
5. Visualize the seed point.

Solver Options

• Include the simulation time, the time step (which can be kept as default), and the number of cores.

Running the Simulation

Now run the simulation. The simulation is completed. Check the results using the bar or by selecting a specific time in the set of time steps.

Manual Method for Static Angle of Repose

1. Block the particle coordinates in Y and X using a cross plot. For this, select the final time step.
2. Take a picture for analysis and draw a tangent line over the particles on the left side.
3. If we plot the Cartesian components, the triangle has these values with the proper scale.
4. Use a trigonometric function to calculate the angle. Repeat the process for the right-hand side.
5. By taking the average, you see that the static angle of repose is 39.62 degrees.

Automatic Method for Static Angle of Repose

1. We will compare the manual result with the one calculated using the automatic method.
2. For this approach, use a Python script. Load the file, and you will see a picture like this:
3. 36 volumes are created to capture the particle distribution.
4. The results are averaged to create the regression lines.
5. Rocky generates a folder containing the results, including the graph, the data, and the regression line information.

And that's all for today. Thank you for watching!

Thanks for watching. Bye!