iMOD User Manual version 4.4 (html)

2.3Installation of MPI software

iMOD 4.3 includes the Parallel Krylov Solver (PKS) package. The Parallel Krylov Solver (PKS) package facilitates running (large) iMOD models on Windows-based multi-core computers potentially resulting in a drastic reduction of runtimes. This package uses Message Passing Interface (MPI) software. Hence, prior to using the PKS-package MPI-software should be installed on your computer too.


The PKS package was implemented for the 64-bit version of iMODFLOW (see Step 5), so the PKS package can be used on Windows-based multi-core 64-bit computer systems, for example on Windows-based laptops and desktops containing Intel CORE i5 or i7 processors or on Windows-based multi-core 64-bit supercomputers.

In iMOD 4.3 the LAK-, MNW-, PST-, SFR- and UZF-packages are not supported by the PKS-package; when an iMOD-model contains one or more of these package the single-core PCG-solver has to be used. So, the PKS-package can be used in combination with the remaining MODFLOW-packages implemented in iMOD; please note that the PKS package can also be used for iMOD models containing the MetaSWAP-concept; this potentially gives another boost to the speed of model simulations containing an iterative state-of-the-art coupling between the saturated and unsaturated zone.

2.3.2Installation steps for the MPI software

The 64-bit iMODFLOW-executable uses the 64-bit MPICH (1.4.1p1) implementation for MPI, hence the following MPI software should be installed prior to using the PKS package.

Note: In order to install the MPI software correctly, you should do this as Administrator:

2.3.3Checking your MPI-installation

We included a general test-program that allows you to check whether the installation of the MPI-software was successful. To perform this check please do the following:

A test is performed using 2 cores; when the test is successful the following message appears:
echo of core 0
echo of core 1

and the ’Window Command Processer’-box should look similar to this:

Please contact your system administrator for help on installing MPI.

2.3.4Info on how to use the PKS-package

It is very easy to adapt existing (pre-iMOD 4.0)-runfiles (*.RUN) for the use of the PKS-package; for more info, see section ’Updating a runfile from iMOD 3.6 to iMOD 4.0’ in Section 10.20.7 of the iMOD User Manual.

The PKS-package can be configured in the ’Solver Settings’-tab of the ’Start Model Simulation’-window of the main menu option ’Tools’; for more info see the iMOD User Manual, Section 7.9.

Once the PKS-package has been configured, there are two ways to start a multi-core model simulation:

You are now set to start iMOD; after completing this chapter new iMOD-users are encouraged to proceed with the tutorials (Chapter 11 of the iMOD User Manual). As a 3D-appetizer consider trying to run and visualize one of the pre-defined tutorial models: follow the steps as described in the next section.