EMA3D Considerations

There are some aspects that must be considered when calling MHARNESS® from EMA3D®. These aspects are listed below.

• The MHARNESS time step will be ignored

• The MHARNESS space step will be ignored

• MHARNESS plane wave excitation is forbidden

• Cables in MHARNESS must possess the same length as those specified in EMA3D

• All capacitance matrices associated with exposed segments must be automatically computed.

• Interpretation of boundary condition circuit termination

• Low frequency approximation

These aspects are further elaborated on below.

The time step specification defined in EMA3D takes precedence over any specifications in MHARNESS. There is thus no need for time step information in MHARNESS. All such information will be ignored.

The space step information defined in EMA3D takes precedence over any specifications in MHARNESS. Furthermore, when MHARNESS cables are specified in EMA3D a cubic mesh is required. All cables within MHARNESS will be assigned a space step equal to that of the EMA3D cubic mesh dimension. There is thus no need for space step information in MHARNESS. All such information will be ignored.

Plane wave excitation is not allowed in MHARNESS. Plane wave excitation must originate within the three-dimensional space of EMA3D. The plane wave specification in MHARNESS will be ignored.

The length of an MHARNESS cable segment is define within the MHARNESS input file. A length is also associated with the meshed geometric line used to define the physical location of the cable within the EMA3D finite difference problem space. When used within EMA3D, the length of the meshed geometric line takes precedence over any length defined in the MHARNESS input file. The MHARNESS cable segment length will thus be modified to fit the length of the EMA3D meshed counterpart.

The conductors in an exposed MHARNESS segment require a reference in order to facilitate impedance matrix computations. The reference is supplied by EMA3D. Manually computing or supplying the impedance matrices is therefore not possible. The impedance matrices must be computed automatically by the algorithms of MHARNESS using the proper reference supplied by EMA3D. This requires that the SEGMENT/COMPLEX or the SEGMENT/COMPLEX2 keyword combination pair be used to define all conductors in an exposed MHARNESS segment.

The interpretation of boundary conditions with a conductance, was discussed in Section 8.10. These same arguments apply to exposed segments, when MHARNESS is employed in EMA3D. Violation of these limitations will illicit an error message and EMA3D/MHARNESS program termination.