Two-dimensional fluidized bed, Discrete Element Model (DEM)
-----------------------------------------------------------
This tutorial shows how to create a two dimensional fluidized bed
simulation using the Discrete Element Model. The model setup is:
+------------------+----------------------------------------------+
| Property | Value |
+==================+==============================================+
| geometry | 15 cm x 90 cm x 0.4 cm |
+------------------+----------------------------------------------+
| mesh | 15 x 45 x 1 |
+------------------+----------------------------------------------+
| solid diameter | 4000 microns (:math:`4000 \times 10^{-6}` m) |
+------------------+----------------------------------------------+
| solid density | 2700 kg/m\ :sup:`2` |
+------------------+----------------------------------------------+
| gas velocity | 42.0 m/s |
+------------------+----------------------------------------------+
| temperature | 298 K |
+------------------+----------------------------------------------+
| pressure | 101325 Pa |
+------------------+----------------------------------------------+
Create a new project
^^^^^^^^^^^^^^^^^^^^
- On the main menu, select ``New project``
- Create a new project by double-clicking on "Blank" template.
- Enter a project name and browse to a location for the new project.
- When prompted to enable SMS workflow, answer `No`, we will use the standard workflow for this tutorial.
.. figure:: /media/gui_new_project.png
:width: 8cm
:alt: create project
Select model parameters
^^^^^^^^^^^^^^^^^^^^^^^
- On the ``Model`` pane, enter a descriptive text in the
``Description`` field
- Select "Discrete Element Model (MFiX-DEM)" in the ``Solver``
drop-down menu.
.. figure:: /media/gui_dem_2d_model.png
:width: 8cm
:alt: model parameters
Enter the geometry
^^^^^^^^^^^^^^^^^^
On the ``Geometry`` pane:
- Enter ``0.15`` meters for the maximum x value
- Enter ``0.90`` meters for the maximum y value
- Enter ``0.004`` meters for the maximum z value
.. figure:: /media/gui_dem_2d_geometry.png
:width: 8cm
:alt: enter geometry
Enter the mesh
^^^^^^^^^^^^^^
On the ``Mesh`` pane, ``Background`` sub-pane:
- Enter ``15`` for the x cell value
- Enter ``45`` for the y cell value
- Enter ``1`` for the z cell value
.. note::
Since there is only one cell in the Z direction, this model is
effectively a 2D simulation.
.. figure:: /media/gui_dem_2d_mesh.png
:width: 8cm
:alt: enter mesh
Create regions for initial and boundary condition specification
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
On the ``Regions`` pane:
- Click the |all_region| (all) button to create a new region that covers the entire domain to be used for the bed initial condition.
- Enter a name for the region in the ``Name`` field ("bed")
- Change the ``To Y`` field to be "ymax/2"
- Click the |bottom_region| (bottom) button to create a new region to be used by the gas
inlet boundary condition.
- Enter a name for the region in the ``Name`` field ("inlet")
- Enter ``0.07`` in the ``From X`` field and ``0.08`` in the ``To X`` field.
- Click the |top_region| (top) button to create a new region to be used by pressure outlet boundary condition.
- Enter a name for the region in the ``Name`` field ("outlet")
.. figure:: /media/gui_tfm_2d_region3.png
:width: 8cm
:alt: create regions
Create a solid
^^^^^^^^^^^^^^
On the ``Solids`` pane, ``Materials`` sub-pane:
- Click the |add| button to create a new solid
- Enter a descriptive name in the ``Name`` field ("solids")
- Enter the particle diameter of ``0.004`` m in the ``Diameter`` field
- Enter the particle density of ``2700`` kg/m\ :sup:`2` in the ``Density`` field
.. figure:: /media/gui_dem_2d_solids.png
:width: 8cm
:alt: new boundary condition
- Select the ``Solids`` pane, ``DEM`` sub-pane
- Check the ``Enable automatic particle generation`` checkbox, so that
the bed Initial Condition, defined later, will be filled with solids
.. figure:: /media/gui_dem_2d_solids2.png
:width: 8cm
:alt: new boundary condition
Create Initial Conditions
^^^^^^^^^^^^^^^^^^^^^^^^^
On the ``Initial conditions`` pane:
- Select the already populated "Background IC" from the region list.
This will initialize the entire flow field with air.
- Enter ``101325`` Pa in the ``Pressure (optional)`` field
.. figure:: /media/gui_tfm_2d_ics1.png
:width: 8cm
:alt: new boundary condition
- Create a new Initial Condition by pressing the |add| button
- Select the bed region created previously for the bed Initial Condition
("bed" region) and click the ``OK`` button.
.. figure:: /media/gui_tfm_2d_newic.png
:width: 8cm
:alt: new boundary condition
- Select the solid (named previously as "solid") sub-pane and enter a
volume fraction of ``0.4`` in the ``Volume Fraction`` field. This will
fill the bottom half of the domain with solids.
- Note the estimated number of particles and inventory (around 3,200 particles or 0.3 kg).
When running DEM simulations on a single core machine,
it is recommended to stay below 100,000 particles to get reasonable run times.
.. figure:: /media/gui_dem_2d_ics2.png
:width: 8cm
:alt: new boundary condition
Create Boundary Conditions
^^^^^^^^^^^^^^^^^^^^^^^^^^
On the ``Boundary conditions`` pane:
- Create a new Boundary condition by clicking the |add| button
- On the ``Select region`` dialog, select "Mass Inflow" from the
``Boundary type`` drop-down menu
- Select the "inlet" region and click ``OK``
.. figure:: /media/gui_tfm_2d_newbc1.png
:width: 8cm
:alt: new boundary condition
- On the "Fluid" sub-pane, enter a velocity in the ``Y-axial velocity``
field of "42" m/s
.. figure:: /media/gui_dem_2d_bcs1.png
:width: 8cm
:alt: new boundary condition
- Create another Boundary condition by clicking the |add| button
- On the ``Select region`` dialog, select "Pressure outflow" from the
``Boundary type`` combo-box
- Select the "outlet" region and click ``OK``
.. note::
The default pressure is already set to 101325 Pa, no changes
need to be made to the outlet boundary condition.
.. figure:: /media/gui_tfm_2d_newbc2.png
:width: 8cm
:alt: new boundary condition
.. note::
By default, boundaries that are left undefined (here the left,
right, front, and back planes) will behave as No-Slip walls.
Select output options
^^^^^^^^^^^^^^^^^^^^^
On the ``Output`` pane:
- On the ``Basic`` sub-pane, check the
``Write VTK output files (VTU/VTP)`` checkbox
.. figure:: /media/gui_tfm_2d_output.png
:width: 8cm
:alt: new boundary condition
- Select the ``VTK`` sub-pane
- Create a new output by clicking the |add| button
- Select "Particle Data" from the 'Output type' drop-down menu.
- Select the "Background IC" region from the list to save all the
particle data
- Click ``OK`` to create the output
.. figure:: /media/gui_dem_2d_newoutput.png
:width: 8cm
:alt: new boundary condition
- Enter a base name for the ``*.vtu`` files in the ``Filename base``
field ("particles")
- Change the ``Write interval`` to ``0.01`` seconds
- Select the ``Diameter`` and ``Translational Velocity`` checkboxes
.. figure:: /media/gui_dem_2d_output_vtk.png
:width: 8cm
:alt: new boundary condition
Change run parameters
^^^^^^^^^^^^^^^^^^^^^
On the ``Run`` pane:
- Change ``Stop time`` to ``1.0`` seconds
- Change ``Time step`` to ``1e-2`` seconds
- Change ``Maximum time step`` to ``1e-2`` seconds
Run the project
^^^^^^^^^^^^^^^
- Save project by clicking the |save| button
- Run the project by clicking the |play| button
- On the ``Run`` dialog, select the executable from the combo-box
- Click the ``Run`` button to actually start the simulation
.. figure:: /media/gui_run_dialog.png
:width: 8cm
:alt: new boundary condition
View results
^^^^^^^^^^^^
Results can be viewed, and plotted, while the simulation is running.
- Create a new visualization tab by pressing the |add| next to the `Model` tab
- Select an item to view, such as plotting the time step (dt) or click
the ``3D view`` button to view the vtk output files.
- On the ``VTK`` results tab, the visibility and representation of the
``*.vtk`` files can be controlled with the menu on the side.
.. figure:: /media/gui_vtk_visible_dialog.png
:width: 8cm
:alt: new boundary condition
- Change frames with the |first|, |back|, |next|, and |last| buttons
- Click the |play| button to play the available vtk files.
- Change the playback speed under the |speed| section on the sidebar.
.. figure:: /media/gui_dem_2d_vtk_view.png
:width: 8cm
:alt: vtk view
.. include:: /icons.rst