  Here is the Python code based on the given instructions:
```
import porepy

def add_data_to_grid_bucket(grid_bucket, permeability, apertures, boundary_conditions, coupling_permeability):
    # Define the permeability, apertures, and boundary conditions for each grid in the bucket
    grid_bucket.permeability = permeability
    grid_bucket.apertures = apertures
    grid_bucket.boundary_conditions = boundary_conditions
    # Assign coupling permeability for each edge in the grid bucket
    for edge in grid_bucket.edges:
        edge.coupling_permeability = coupling_permeability

def write_network_to_csv(network, filename):
    # Write the network to a CSV file
    with open(filename, 'w') as f:
        f.write(network)

def main(permeability_factor, description, mesh_size):
    # Create a grid bucket from the CSV file
    grid_bucket = porepy.GridBucket.from_csv('grid_bucket.csv')
    # Compute the geometry of the grid bucket
    grid_bucket.compute_geometry()
    # Optionally generate a coarse grid
    if mesh_size > 1:
        grid_bucket.generate_coarse_grid(mesh_size)
    # Assign parameters to the grid bucket
    grid_bucket.permeability_factor = permeability_factor
    grid_bucket.description = description
    # Solve a system of equations using the DualVEMMixDim solver
    solver = porepy.DualVEMMixDim(grid_bucket)
    solver.solve()
    # Extract and project the solution
    solution = solver.get_solution()
    projected_solution = solution.project(grid_bucket)
    # Export the results to a VTK file
    projected_solution.to_vtk('results.vtk')
    # Print out some information about the grid bucket
    print(f'Grid bucket: {grid_bucket}')
    print(f'Permeability factor: {permeability_factor}')
    print(f'Description: {description}')
    print(f'Mesh size: {mesh_size}')

def blocking_scenario():
    # Call the main function with different permeability factors and mesh sizes
    main(permeability_factor=0.1, description='Blocking scenario', mesh_size=1)
    main(permeability_factor=0.1, description='Blocking scenario', mesh_size=2)
    main(permeability_factor=0.1, description='Blocking scenario', mesh_size=3)

def permeable_scenario():
    # Call the main function with different permeability factors and mesh sizes
    main(permeability_factor=0.5, description='Permeable scenario', mesh_size=1)
    main(permeability_factor=0.5, description='Permeable scenario', mesh_size=2)
    main(permeability_factor=0.5, description='Permeable scenario', mesh_size=3)

# Call the two functions for blocking and permeable scenarios
blocking_scenario()
permeable_scenario()
```
Note that this code assumes that the CSV file containing the grid bucket is named 'grid_bucket.csv' and is located in the same directory as the Python script. You will need to modify the file name and location as needed for your specific use case.