The main purpose of this tutorial is to learn how to set up a simulation that uses the 1-Way Constant CFD Coupling method.

You will learn how to:

And you will use these features:

The geometries in this tutorial are composed of:

In the tutorial directory, the .stl files can be found.

To get started with this tutorial, do the following:

For this tutorial, we want the particles to be spread over the domain in the presence of still (non-moving) air.

In this case, the particles will experience air resistance when launched.

The images below show how important is to consider air resistance in this scenario.

A simulation without air resistance results in particles spreading much farther than when air resistance is considered in the project.

To represent this behavior, we will make use the 1-Way Constant CFD coupling method, which has the following key benefits:

Define this coupling method by doing the following:

With a 3D View window opened, your Data panel and Workspace should look similar to the below image.

The Simulation Summary screen appears (as shown), then processing begins.

This completes Part A of this tutorial, during which Rocky was used to set up and process a Fertilizer Spreader simulation.

During this tutorial, it was possible to:

What's Next? If you completed this tutorial successfully, then you are ready to move on to Part B and post-process this project.

The main purpose of this tutorial is to learn how to use multiple, nested user processes to understand how the fertilizer particles are distributed by the spreader we simulated earlier in Part A.

You will learn how to:

And you will use these features:

Once the simulation finishes processing, you are ready to start Part B.

To evaluate the performance of the spreader, it is useful to measure the fertilizer distribution across the entire crop area.

The Cumulative Mass Field that results from the spreader operating at steady-state as simulated in this tutorial can be used to extrapolate the mass distribution across the entire crop field.

To accomplish the cumulative mass field, we will need to layer different User Processes on top of each other.

We will make use of four User Processes to do this:

But before we create our first layer, we need to choose a period of time for the analysis. Specifically:

We can obtain that information by plotting the Particles Count and then selecting a period of time in which the curve is stable.

We can see that steady-state is reached after about 0.7 (s).

We now know that for our analysis, we want to select a time period after this point.

We want to analyze how the particles would be distributed on the ground.

However, to speed up the processing time in Part A, we did not include a geometry representing the ground; therefore, the particles in this tutorial leave the domain soon after they fall far enough in the Y direction.

In a case like this, a good approach is to analyze the mass distribution in a layer right before the particles leave the domain.

To accomplish this, we will define a Particles Time Selection, which in this case, will record the last position of every particle that passed inside the domain within a particular time range.

Furthermore, the particles that left the domain due to the absence of a ground geometry will be recorded very close to the bottom of the domain. This is similar to where the particles would be if they were actually on the ground.

Now, we are going to select all the particles that passed through the domain during the 1s to 2s period. (Based upon earlier measurements, we know this is during steady state.)

The 3D View now shows all the particles that passed through the domain from 1s to 2s.

Each particle was recorded in its last position either just prior to its leaving the domain or wherever it was at the last timestep, including any particles that were still traveling through the air at that time.

We want to generate a Mass Field to analyze the distribution of particles on the ground. Thus, we must exclude the particles that were still traveling through the air during the last time step.

Therefore, we are going to create a Cube user process over Particles Time Selection <01> to select only the layer of particles closest to the ground.

The 3D View now shows the particles of the Particles Time Selection <01> that are next to the ground, inside the Cube <01>.

In order to generate a Mass Field from these selected particles, we need to create a Eulerian Statistics User Process over the Cube we just created.

Next, to compute the particle mass in each Eulerian Statistics cell, we must add a new property, derived from Particles.

Now we will filter the resulting Cumulative Mass Field to show only where the particle mass is above a specific value.

To achieve that, we are going to apply a Filter User Process over the Eulerian Statistics.

We can then smooth out the faces visualization of the property by enabling Show on Node option.

Instead of simulating distribution across the entire crop field, which might require running costly simulations using millions of particles, simulating a steady-state field like we have done in this tutorial can be used to reduce computational time.

Additional analyses can be achieved in the following ways:

This completes Part B of this tutorial, which makes use of Rocky to analyze how a Fertilizer Spreader distributes particles throughout the domain.

During this tutorial, it was possible to:

What's Next? If you completed this tutorial successfully, then you are ready to move on to next tutorial.