Two Dimensional Fluid 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| 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| 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 Y`` field. - Click the |top_region| 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`` check-boxes .. figure:: /media/gui_dem_2d_output_vtk.png :width: 8cm :alt: new boundary condition Change run parameters ^^^^^^^^^^^^^^^^^^^^^ On the ``Run`` pane: - Change the ``Stop Time step`` to ``1.0`` seconds - Change the ``Time step`` to ``1e-2`` seconds - Change the ``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