4.1.2. Forward Modeling¶

The program dcipf3d_55.exe performs the 3D forward modelling of DC resistivity or IP data on tensor meshes.

4.1.2.1. Running the Program¶

To run the executable, open a command window and type the following:

Essentially you are calling the path to the executable followed by the path to the input file .

4.1.2.2. Setting Number of Threads with Open MPI¶

Before running the executable, the number of threads used to carry out all simultaneous processes can be set with Open MPI. This is set in the command window before running the executable. To set the number of threads (nThreads ), use the following syntax:

Windows computer: “set OMP_NUM_THREADS=nThreads”

Linux (bash shell): “export OMP_NUM_THREADS=nThreads”

Linux (csh shell): “setenv OMP_NUM_THREADS nThreads”

4.1.2.3. Units¶

DC data: measured voltage normalized by the transmitter current (V/A)

IP data: Depends on the IP data type set in the survey file, the data are either secondary voltage or apparent chargeability

Conductivity model: S/m

Chargeability model: intinsic chargeability - unitless from [0,1)

Note

If you use the linear IP formulation, the chargeability model and predicted apparent chargeability data can use any normalization you want. That is, your chargeability model could be V/V, mV/V or ms and the resulting apparent chargeabilities would be V/V, mV/V and ms, respectively.

4.1.2.4. Output Files¶

The program dcipf3d_55.exe creates the following output files:

dc3d.dat: Predicted DC data (output if data type set to dc )

ip3d.dat: Predicted IP data (output if data type set to ip )

ip3d_lin.dat: Predicted IP data (output if data type set to ipL)

obs.loc: if the survey file used surface format, the code will output a general locations file that contains the elevations of the electrodes projected to the discrete topography.

dcipf3d.log: Log file which provides details about the parameters used in the forward modelling and diagnostic information about the results.