Moving wall for particle packing

MFiX How to
,
#1

Hi everyone,

I am trying to simulate a pull-up test of a hollow cylinder filled with bulk material, like particle packing see below.

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The figure is from reference Redirecting

Here is my geometry and domain. The inner blue wall is expected to have a constant lifting velocity until its open buttom reaches a speficied height. My question is how to give the blue wall a constant lifting velocity if its open buttom below a speficied height? If a or some .f file(s) should be edited, how to edit them. Are there any examples?

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Thank you very much.

#2

Hi, I supply my former question today. Is the lifting wall for pure granular flow enabled by specifying the wall v-velocity for particles in the following pane? From this post ( Johnson-Jackson boundary condition with cut-cell), I known wall v-velocity for particles can not be specified with the cut-cell grid. Maybe it can be specified with the Cartesian grid. How to enable the Cartesian grid?

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#3

The keyword CARTESIAN_GRID is not exposed directly in the MFiX GUI, it is set to the correct setting depending on whether you are using STL geometry, or a few other types of geometry (quadrics, polygon, or mesh) - here’s the code where it’s set, in mfixgui/vtk_widgets/geometry_engine.py:

        # Export geometry
        geometry = self.collect_toplevel_geometry()
        use_stl = False
        if geometry:
            self.project.updateKeyword('cartesian_grid', True)
            self.project.updateKeyword('use_stl', True)
            use_stl = True
            # write file
            stl_writer = vtk.vtkSTLWriter()
            stl_writer.SetFileName(file_name)
            stl_writer.SetInputConnection(geometry.GetOutputPort())
            stl_writer.Write()
        elif self.project.get_value('n_quadric', None) is not None:
            self.project.updateKeyword('cartesian_grid', True)
        elif self.project.get_value('use_msh', False):
            self.project.updateKeyword('cartesian_grid', True)
        elif self.project.get_value('use_polygon', False):
            self.project.updateKeyword('cartesian_grid', True)
        else:
            self.project.updateKeyword('cartesian_grid', False)
            self.project.updateKeyword('use_stl', False)
```
1 Like
#4

Thank you @cgw . I have found a shearing flow case (a testing case in MFIX) in which a wall velocity is specified. In this case, the wall do not move away, imposing a constant velocity to the liquid attached to the wall instead. Hence, I feel the cylinder wall could not be pulled up against time through specifying the wall V-velocity. Anyway,thanks.

1 Like
#5

Hello,

I am also trying to move a wall with a constant velocity. Could you please guide me about the shearing flow case (a testing case in Mfix you are talking)? I would be grateful to your help.

Thank you very very much.