Simulation and Analysis of the FT4 Rheometer Flow Energy test

This section provides instructions on running a simulation of the FT4 Rheometer Basic Flow Energy (BFE) and Specific Energy (SE) tests in EDEM and extracting the relevant data automatically using EDEMpy.

The FT4 Basic Flow Energy test consists of force and torque measurements on an impeller blade moving through a cylindrical bed of granular material. The test is performed at different magnitudes of helical velocity of the blade, also known as 'blade tip speed' as shown in Figure 1. The work done by the impeller blade is calculated from the force and torque measurements and is used as an indication of the flowability of the material. The standard test procedure at a given blade tip speed is shown in Figure 2.

Figure 1. Kinematics of the impeller blade and flow energy calculation


Figure 2. DEM Simulation of the Freeman FT4 Rheometer test


The relatively high velocities of the blade and the helical motion of the impeller through the sample lead to a complex state of stress and a dynamic flow regime. These conditions may approximate the ones induced in dynamic systems such as high shear granulators and mixers. The results are less relevant for systems in the quasi-static flow regime.

Prerequisites

The simulation and analysis procedure described in this section requires EDEM version 2022 or later. The Calibration Kit examples are installed in the Altair installation folder > EDEM (version) > examples > Calibration Kits. Copy the Calibration kit and examples to a processing folder before they are configured and run.

The analysis described in this section uses EDEMpy. For more information about EDEMpy, see the EDEM Help documents.

Running Simulations

EDEM decks are provided for the standard test procedure using the small (50ml) and medium (160ml) cells. The decks are categorized in folders with the following naming convention: FT4_[cell volume]_[blade speed]. For example, the files in folderFT4_160_40 correspond to the 40 mm/s blade tip speed test in the 160 ml cell.

You can run the simulations directly in EDEM. Run the deck provided in EDEM and do the following:
  1. Open the deck and setup the simulation parameters.
  2. Run the simulation till the end.
    Note: One second of simulation time is allowed for the filling stage of the test before the blade motion begins. If more time is required, the kinematics should be adjusted appropriately.

Automatic Post-processing of results with EDEMpy

You can automatically obtain the responses of interest in the flow energy test such as the conditioned bulk density, Basic Flow Energy (BFE), Specific Energy (SE), force and torque on the blade, simulation input parameters, and test operation parameters from the EDEM simulation data using the FT4_Analyst.py script provided.

The post-processing script utilizes the EDEMpy library to locate all EDEM decks in the folder containing the script and subfolders. Finally, it generates reports and figures with all the relevant data.

The analysis settings for the script are defined in the FT4_Analyst_Settings.txt file, as shown in Figure 3. The settings files for all standard tests are provided along with the EDEM decks. If you have used a custom test procedure, the timings must be adjusted accordingly. If you have omitted a stage from a custom simulation, the relevant times can be set to zero, but the format of the file remain the same.

Figure 3. Contents of the FT4_Analyst_Settings file


You can post-process multiple simulation decks with the script by arranging the files into one of the two configurations as shown in Figure 4. The second configuration is recommended, as it allows for individual settings files for each EDEM deck, and therefore post-processing of different types of tests can be done simultaneously. In the first configuration, a single settings file is read for post-processing all decks.

Figure 4. File configuration for post-processing multiple simulations using the FT4_Analyst script


To run the FT4_Analyst_v3.py script:
  1. Arrange the files as shown in Figure 4.
  2. Open a blank or existing EDEM simulation file, and go to EDEM Analyst > Run > EDEMpy Script.
  3. Go to Select File > Run Script and then select the FT4_Analyst_v3.py script.
    1. Reports and graphs will be generated in the master folder. Individual reports will contain all the relevant data and the summary report will contain only time-averaged results.
      Only complete simulations with the corresponding settings files will be post-processed. Otherwise the script will produce error messages as shown in Figure 5, and then move to the next simulation in the folder tree.
      Note: All simulation files must have unique folder names and simulation names. If the simulation names are identical, the results report will be overwritten.
      Figure 5. Possible error messages


Script Version changes

Version 3 of the FT4 Rheometer Analyst script is designed to work with EDEM version 2022.0 (and later) and EDEMpy. This EDEMpy version includes a change where creatordata is indexable, and all references to creatordata have been replaced with creatordata[0].