dual

    Dual porosity formulation. There are three sets of parameter values at any nodal position, for which property values must be defined. Nodes 1 to N (see macro coor for definition of N) represent the fracture nodes, nodes N + 1 to 2N the first matrix material, and nodes 2N + 1 to 3N the second matrix material. When zones are used with the dual macro, additional zones are automatically generated.

    See instructions for the macro zone for a more detailed description. The dual parameters are only defined for the first N nodes.

    Input Variable Format Default Description
    IDUALP integer  
    Solution descriptor for dual porosity solution.
    IDUALP = 0, information is read but not used.
    IDUALP ≠ 0, dual porosity solution is implemented
    For the special case of IDUALP = 2, the permeabilities and conductivities are scaled by the volume fraction, i.e., \(k = vf * k\).
    VOLFD1 real 0.001 Volume fraction for fracture portion of the continuum.
    VOLFD2 real 0.5 Volume fraction for the first matrix portion of the continuum.
    APUVD real
    		Length scale for the matrix nodes (m).

    The volume fractions VOLFD1 and VOLFD2 are related to the total volume by

    \(VOLFD1 + VOLFD2 + VOLFD3 = 1.0\)

    where VOLFD3 is the volume fraction of the second matrix node. If permeability model IRLP = 4 is selected in control statement rlp, VOLFD1 is calculated from RP15 (fracture porosity) in that control statement.

    The following is an example of dual. In this example, the dual porosity solution is implemented for all nodes from 1 through 140. The volume fraction for the fracture is 0.006711409, the volume fraction for the first matrix portion is 0.335570470, and the length scale for the matrix nodes is 0.1 m.

    dual      
    1      
    1 140 1 0.006711409
           
    1 140 1 0.335570470
           
    1 140 1 0.10
           

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