Moving wall for particle packing

Hi everyone,

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


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?

Thank you very much.

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?

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)
```

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.