The 1-way coupling can use either a steady or transient flow field. For the 1-way coupling, select Fluent Solution Properties and change the Initialization Method to Solver Controlled;

Figure 2.52: For 1-way coupled simulations, the Initialization Method should be set as "Solver Controlled" in the Fluid Flow Solution Properties.

For a 1-way transient coupling, the option to Export the transient data must be enabled in the Rocky Export entry in Fluent.

Figure 2.53: Enable export the transient data.

To use the flow field in the 1-way coupled simulation, link the Fluent Solution to the Rocky Setup.

Figure 2.54: Fluent-Rocky 1-way coupling.

For sharing the geometry between projects, link the Geometry of the Fluid project to the Geometry of the Rocky project. Doing so, the geometry will be automatically imported into Rocky.

Figure 2.55: Sharing the geometry between projects.

After the CFD solution is ready, when opening Rocky, the CFD Coupling entry in the Data Tree has the 1-Way Fluent mode selected.

Figure 2.56: 1-Way Fluent mode selected in Data Tree.

Open the 1-Way Fluent Data Editor and edit the coupling settings as usual.

Figure 2.57: Data Editor for the 1-way steady-state coupling between Rocky and Fluent.

After run the simulation, the CFD and DEM results of the unresolved 1-way coupling can be simultaneously post-processed in Rocky Fluid. Quantities such as pressure and velocities can be analyzed and shown in the 3D view together with the particles.

Figure 2.58: The coloring tab of the 1-Way Fluent Data Editor allows the selection of which fluid information should be showed in the 3D view.

Figure 2.59: Vectors colored by the magnitude of the fluid velocity give insight to the flow field in 1-way coupled simulations.

Drag the Fluent analysis onto the Project Schematic and set up the Fluent Project.

Important: You can only set up the 2-way coupled project if the Fluent Project is set up. Rocky looks for the .cas file for importing the necessary files for the 2-way coupling.

Drag a Rocky Analysis to the Project Schematics. Do not drop it on top of the Fluent setup.

Important: Do not drop it on top of the Fluent setup. The link must be created manually after both the two systems are placed at the Project Schematic.

Figure 2.60: Draging a Rocky Analysis to the Project Schematics.

Drag the Fluent Setup onto the Rocky Setup.

Figure 2.61: Fluent-Rocky 2-way coupling.

Select Unresolved as the 2-way coupling mode.

Figure 2.62: Unresolved 2-way coupling mode.

If the Fluent setup has Energy Model on, enable the Thermal in the Momentum tab of the Physics Data Editor in Rocky.`

Figure 2.63: Enabling the Thermal in the Momentum tab of the Physics Data Editor in Rocky.

When opening Rocky, the CFD Coupling entry at the Data Tree has the 2-Way Fluent mode selected.

Figure 2.64: CFD Coupling entry in the data tree has 2-way Fluent coupling selected.

Open the 2-Way Fluent data panel and edit the coupling setup as usual.

Figure 2.65: The Unresolved 2-way coupling mode is enabled, and the coupling setting can usually be edited.

Set up the Fluent execution setting - select to run either in serial or parallel and the number of CPU processes that are used to solve CFD equations.

Important: As the Fluent run is controlled by Rocky in the 2-way coupling, the execution settings defined in the Rocky setup are used.

Figure 2.66: The Fluent tab allows the definition of the execution mode and the data used as the initial fluid field.

For prescribing an initial fluid field for the CFD solution, the .dat file should be imported at the Rocky setup.

Important: The current version does not allow the initial flow field to be imported from another Fluent run within the workbench. The fluent data file must be imported using the Fluent tab in Rocky.

For sharing the geometry between projects, link the Geometry of the Fluid project to the Setup of the Rocky project. Doing so, the geometry will be automatically imported into Rocky.

Figure 2.67: Unresolved 2-way coupled simulation with geometry shared between Rocky and Fluent.

The CFD and DEM results of the unresolved 2-way coupling can be simultaneously post-processed in Rocky by opening the Setup entry of the Rocky project. Fluid quantities such as pressure and velocities can be analyzed and shown in the 3D view together with the particles.

Figure 2.68: Integrated fluid and particles post-processing inside Rocky.

The post-processing of additional fluid data can be done inside Fluent. For this purpose, a new Results component should be linked to the Fluent Solution of the coupled Rocky project.

Figure 2.69: The Fluent Solution entry should be used to send the fluid data for external post-processing.

The Fluent Solution entry in the Rocky project should be used for sending the fluid data to another software, such as a post-processing software or a structural analysis.

Figure 2.70: Input and output parameters created in Rocky are available in Workbench.

For updating changes made to an upstream step, such as changes in a Fluent boundary condition or CFD mesh, select Refresh from the Rocky Setup entry.

Important: Any change in the Fluent Setup should be made in the Fluent Project that is linked to the Rocky simulation, not from the 2-way Fluent Data Editor in the Rocky UI. The reason is that the CFD setup from the Fluid Flow project will be copied and used as the base setup for the coupled simulation. Any changes made using Rocky will be overwritten when updating the workbench project.

Figure 2.71: If something is changed in an upstream component, the Refresh option in the Setup entry should be used to update the Fluent project used in the coupled simulation.

Inputs and Outputs parameters of the DEM simulation are exposed in the workbench as any other Ansys solver and can be used to evaluate several design points automatically.

Figure 2.72: The Fluent solution entry should be used for sharing the fluid data with another software, such as for structural analysis.

Drag the Fluent analysis and set up the Fluent Project.

Drag a Rocky Analysis to the Project Schematics. Do not drop it on top of the Fluent setup.

If the DEM simulation has no walls, you can Remove the Geometry Component.

Figure 2.73: Remove Geometry component.

Select Setup in the Rocky Project and click Edit. Select Semi-Resolved as the 2-way coupling mode.

Figure 2.74: Semi-Resolved mode selected.

When opening Rocky, the CFD Coupling entry at the Data Tree has the 2-Way Fluent Semi-Resolved mode selected.

Figure 2.75: 2-Way Fluent Semi-Resolved mode selected.

In the 2-Way Fluent Semi-Resolved Data Editor, the coupling setup can be edited as usual.

Figure 2.76: 2-Way Fluent Semi-Resolved settings.

For sharing the geometry between projects, link the geometry between the Fluid project and the Rocky Setup projects. Doing so, the geometry will be automatically imported into Rocky.

Figure 2.77: Sharing the geometry between projects.

For the Semi-Resolved coupling, fluid data cannot be post-processed in Rocky. For post-processing fluid data, add a new Results component system and link it to the Rocky project Fluent Solution.

Figure 2.78: Post-processing fluid data in 2-way semi-resolved coupled runs.

Set up your simulation as you wish, then you will have to stipulate within Rocky which geometry of your simulation you want to couple.

To do this, right-click on the desired geometry, then click on Convert to and then on System Coupling Wall.

Figure 2.81: Convert Geometry to System Coupling Wall

Figure 2.82: System Coupling Wall Data Panel

Click on File and then on Write System Coupling file. This step creates a file with information about where your Rocky file is for System Coupling.

Figure 2.83: Write System Coupling File Rocky

Figure 2.84: System Coupling Participant file

Open your project in Ansys Mechanical and set the Initial Temperature and the System Coupling Region using the Transient Thermal option.

Figure 2.85: Transient Thermal Ansys Mechanical

Set the System Coupling Region, as shown in the figures below:

Figure 2.86: Details of System Coupling Region

Figure 2.87: System Coupling Region in Mechanical

Export the System Coupling File, by right-clicking on Transient Thermal and then on Write System Coupling Files.

Figure 2.88: Write System Coupling File Mechanical

Open your project in the Ansys Workbench and set the 2-way Thermal Coupling using the Transient Thermal option.

Figure 2.89: Transient Thermal in Workbench

Learn more at About Rocky and Ansys Workbench Integration

Open System Coupling and select a folder of your choice.

Figure 2.90: Transient Thermal in Workbench

In the Data Panel, right-click Setup and then click Add Participant.

Figure 2.91: Add Participant in System Coupling

In the Add Participant window, select Input File and add the System Coupling File (.SCP) you saved from Rocky.

Figure 2.92: Add Participant: System Coupling File Rocky

Repeat step 1, and in the Add Participant window, select Input File and add the System Coupling File (.SCP) you saved from Mechanical.

Figure 2.93: Add Participant: System Coupling File Mechanical

Your Data Panel must have both Rocky and Mechanical files:

Figure 2.94: System Coupling Participants

In the Data Panel, right-click Setup and then click Add Coupling Interface.

Figure 2.95: Coupling Interface

Right Click on Coupling Interface and then click on Add Data Transfer.

Figure 2.96: Coupling Interface Data Panel

Figure 2.97: Add Data Transfer

Set the Data Transfer to Rocky as show in the figures below:

Figure 2.98: Data Transfer Rocky

Figure 2.99: Data Transfer Rocky Setup (Temperature)

Repeat step 6, and set the Data Transfer to Mechanical as show in the figures below:

Figure 2.100: Data Transfer Mechanical

Figure 2.101: Data Transfer Mechanical Setup (Heat Flow)

In the example below the Rocky Data Transfer is named as Temperature and the Mechanical Data Transfer is named as Heat Flow:

Figure 2.102: Data Transfer Rocky and Mechanical

In Solution Control define the End Time and the Time Step Size.

Figure 2.103: Solution Control

In Output Control, click on Results, and then on Type and select the Every Step option, as shown in the figure below:

Figure 2.104: Output Control

Click on Start Solve.

Figure 2.105: Start Solve

After solving your simulation, the post processing fase is carried out using the EnSight. Click on EnSight:

Figure 2.106: System Coupling After Solving

Figure 2.107: Access EnSight through System Coupling

The geometries will appear in EnSight as shown in the figure below, one on top of the other, if you prefer you can separate them:

Figure 2.108: Post Processing EnSight

Figure 2.109: Changing the Translation

To see the results you have to drag the desired parameter to the geometry you want to see the result:

Figure 2.110: Dragging the desired parameter to the Geometry

Figure 2.111: Geometries Solved

Figure 2.112: Parameter Solved added to the geometry

For the Rocky side, the first difference is that now, there are 2 Coupling Types options for the System Coupling Wall. For the 2-Way Structural Coupling, just select the Structural one. And for the 2-Way Thermal, just select the Thermal one.

Figure 2.113: Coupling Types for the System Coupling Wall

The rest of Rocky setup, as well the Write System Coupling file is the same as 2-Way Thermal.

Figure 2.114: Write System Coupling File Rocky

The difference from the Mechanical side is that now, the Transient Structural system for the Workbench that will be needed, as show in this image

Figure 2.115: Transient Structural Ansys Mechanical

The Model data tree setup process follows the same default Structural one, with just the System coupling regions as already described for the Thermal.

Figure 2.116: Project data tree for the Transient Strctural

One important point here is that the Time Step inside the Analysis System, for most of the cases, will need to have a small number, as the DEM-SPH collisions will happen in a small-time fraction, and as Mechanical is an Implicit Solver, the Time Step here will need to be smaller. With the biggest time steps, Mechanical will not be able to converge, and a High Element Distortion message will be shown in the System Coupling UI.

Figure 2.117: Time Step in Analysis Settings for the Transient Structural

After the setup, the System Coupling Region must be exported.

Figure 2.118: Write System Coupling Files

For the System Coupling side, all first steps are still the same. The only difference will be at Add Data Transfer, which now will have the Add FSI Data Transfer, which mainly will connect the forces data from Rocky, and send it to Mechanical.

Figure 2.119: Add FSI Data Transfers inside System Coupling

During the System Coupling solve process, it will be noticed that now, the Data Transfer will be the Force (Rocky to Mechanical) and Incremental Displacement (Mechanical to Rocky).

Figure 2.120: Force and Incremental Displacement Data Transfers

In the latest part, which is the post-processing, the two options remain: use Ensight directly from the System Coupling UI, or open Rocky and analyze the DEM-SPH trajectory and the Displacement results. At Ensight, new Variables are available, such as Force, Incremental Displacement, and Displacement Since Mesh Import, and for the Rocky side, the Displacement property will show up.

Figure 2.121: Ansys Ensight Post-Processing

Figure 2.122: Ansys Rocky Post-Processing

The Rocky setup must have the Thermal model enabled.

The Fluent setup must have the Energy Equation turned on.

For 2-way coupled simulations, the walls must have Shell Conduction enabled in the Fluent setup, regardless of the Thermal Conditions option chosen.

Giving the wall thickness (thin wall model) but not turning on the shell conduction model does not make the wall compatible with the coupling.

Only walls in participating fluid domains can be thermally coupled to the DEM solution.

Import the Fluent case file and set up the required models listed in the Interactions, Coupling, Zones and Interfaces, Fluent and Variables tabs, as required for any 2-way coupled simulation.

Click the 2-Way Fluent entry in the Data Panel and navigate to the Boundaries tab in the Data Editors. Clicking on Load Fluent Boundaries will open a window listing all the compatible boundaries.

Tip: Check the Requirements entry to understand the compatibility criteria.

Figure 2.124: 2-way Fluent Boundaries tab in the Data Editors .

Select the walls you want to use for the thermal coupling.

Figure 2.125: Select the walls in the Load Fluent Boundaries.

For each selected wall, a new entry will appear under Geometries in the Data panel. These walls have specific icons as they are thermally coupled.

Figure 2.126: New entries under Geometries in the Data panel.

Unselecting the wall from the Load Fluent Boundaries list will remove the coupled wall from the Geometry list, as well as any user process linked to the coupled wall.

The coupled walls have fewer options compared to the standard walls as some models are not supported, such as wear and replication.

Figure 2.127: Options available for a coupled wall.

Figure 2.128: Options available for a standard wall.

Select the Material to be assigned to the coupled wall.

Important: The mechanical properties of the assigned material will be used for computing contact forces for collisions between the particles and the wall, but the thermal properties required for the conductive heat transfer calculation will be extracted from Fluent.

Run the coupled simulation normally.

Two additional transient properties are available for coupled walls - Temperature and Thermal Conductivity. These triangle properties can be shown in 3D views or used to generate quantitative analyses such as time plots, histograms, or output parameters.

Figure 2.129: Additional transient properties for coupled walls.

Figure 2.130: The wall temperature, initially at 300K, increases as hot particles (500K) collide with the wall.

For setting up a 1-way thermal coupled simulation, there is only one additional step that must be completed. In the Rocky Export plugin, select Configure one-way export and then Select Wall Thermal Zones.

Figure 2.131: Select Wall Thermal Zones in the Rocky Export plugin.

The Thermal Wall Selector window will list all the walls that are compatible with the 1-way thermal coupling between Rocky and Fluent.

Figure 2.132: List of all the walls compatible with the 1-way thermal coupling between Rocky and Fluent in the Thermal Wall Selector window.

Pick the walls that you wish to participate as coupled walls.

Figure 2.133: Walls selected in the Thermal Wall Selector window.

Run the simulation normally and export the results to Rocky using the Rocky Export Plugin.

Figure 2.134: Results exported to Rocky using the Rocky Export Plugin.

In Rocky, enable Thermal and select Fluent (Fluid -> Particle) as the coupling mode.

Figure 2.135: Fluent (Fluid -> Particle) Selected.

Select the F2R file that was exported from Fluent. Set up the required models listed in the Interactions and Coupling tabs, as required for any 1-way coupled simulation.

Click the 1-way Fluent entry in the Data Panel and navigate to the Boundaries tab in the Data Editors.

Figure 2.136: 1-way Fluent Boundaries tab in the Data Editors.

Clicking on Load Fluent Boundaries will open another window listing all the compatible boundaries. Tip: Check the Requirements entry to understand the compatibility criteria.

Figure 2.137: Load Fluent Boundaries listing all the compatible boundaries.

Select the walls you want to use for the thermal coupling.

Figure 2.138: Walls to be selected for the thermal coupling.

For each selected wall, a new entry will appear under Geometries in the Data panel. These walls have specific icons as they are thermally coupled.

Figure 2.139: New entries under Geometries in the Data panel.

Unselecting the wall from the Load Fluent Boundaries list will remove the coupled wall from the Geometry list, as well as any user process linked to the coupled wall.

The coupled walls have fewer options compared to the standard walls as some models are not supported, such as wear and replication.

Figure 2.140: Options available in Coupled Walls.

Select the Material to be assigned to the coupled wall.

Important: The mechanical properties of the assigned material will be used for computing contact forces for collisions between the particles and the wall, but the thermal properties required for the conductive heat transfer calculation will be extracted from Fluent.

Run the coupled simulation normally.

Additional properties are created for the coupled walls. These can be used for quantitative analyses, such as time plots and histograms, for creating output parameters or for coloring the wall triangles in a 3D view.

Figure 2.141: Properties created for the coupled walls.

Open the Ansys optiSLang program.

From the main Ansys optiSLang screen, under New Project, click Guided (as shown) to open the Solver Wizard.

From the Solver Wizard, search for Rocky, and then under Interfaces, select the ROCKY option (as shown).

From the Select project file dialog, navigate to and then select the already-processed Rocky project file you want to use, and then click Open (as shown).

. From the Choose Rocky script to export results dialog, select the script (.py) file you want optiSLang to use for the exported output variables, and then click Open (as shown).