3.2.2. Forward Modeling Input File

The forward problem for both DC and IP data is solved using the executable program dcipf3d_55.exe. The lines of input file are as follows:

Line #	Description	Description
1	Data Type	data being modeled: dc | ip | ipL
2	Tensor Mesh	path to tensor mesh file
3	Survey File	path to survey file
4	Conductivity Model	conductivity model
5	Chargeability Model	chargeability model
6	Active Topography Cells	topography
7	pot	output potentials file
8	tol	relative tolerance for solver
9	vec	Max number of vectors to store

Fig. 3.2 Example input file for modeling DC data (Download ).

3.2.2.1. Line Descriptions

• Data Type: the user chooses a flag specifying the data which are modeled by the program:

  • dc: DC resistivity data are modeled. Although the line for the chargeability model is ignored, something must be put there as a placeholder.

  • ip: IP data are modeled with a non-linear formulation.

  • ipL: IP data are modeled with a linear formulation.

• Tensor Mesh: file path to the tensor mesh file

• Survey File: file path to the survey file

• Conductivity Model: file path to the conductivity model

• Chargeability Model: The user may enter

  • the file path to a chargeability model

  • the flag VALUE followed by a float representing a homogeneous background conductivity

• Active Topography Cells: Here, the user can choose to define the surface topography.

  • null: all cells lie below the surface topography

  • topography file: the user supplies the file path to a topography file which has the xyz locations for discrete topography

  • active cells model: the user supplies the file path to an active cells model which 1 denotes cells below the surface and 0 denotes cells above

Note

If the survey file is surface format, the electrode locations will be projected to the discretized surface when topography is included. If the survey file is general format, electrodes may be modeled as being in the air.

• pot: Enter a flag of 1 to output a file containing the potentials or enter a flag of 0 to ignore.

• tol: relative tolerance for solving the system. A default value of 1e-5 works well.

• vec: An integer which specifies how many solution vectors are to be stored in the computer’s memory at one time. Use -1 to store all vectors in memory.