# iMOD User Manual version 4.4 (html)

#### 11.7Tutorial 7: Interactive Pathline Simulator

This tutorial gives a brief overview of the capabilities of the Interactive Pathline Simulator Tool (IPS). It allows the user to demonstrate and examine the flow behaviour of the groundwater system in an interactive manner. For a full description of all IPS-functionalities, see Section 7.15.

Outline

This is what you will do:

• • Load an existing model simulation into the IPS tool;

• • Define starting points;

• • Start a pathline simulation and represent them in different ways;

• Filter pathlines depending on their type of capture;

Required Data

For this tutorial you need the following iMOD Data Files/folders:

• • The entire folder (and subfolders) {installfolder}\tutorials\TUT_IPS\, containing:

• – BOUNDARY.IDF – model boundary;

• – SURFACE_LEVEL.IDF – uppermost elevation of the model;

• – AQUITARD_TOP.IDF – top of the intermediate aquitard;

– AQUITARD_BOT.IDF – bottom of the intermediate aquitard;

– BEDROCK.IDF – bottom of the underlying aquifer;

• – . \RESULTS\IMODPATH.RUN – imodpath runfile (see Section 8.6.6) referring to all result files that are needed for the particle tracking simulation.

Getting Started

• 1. In the iMOD Manager click the icon ’Open Map’, navigate to the folder

• 2. From the main menu select Toolbox, than Pathline Simulation, go to Interactive Pathline Simulation (IPS) and Start IPS.

• 3. Select from the folder {installfolder}\tutorials\TUT_IPS\RESULTS the file IMODPATH.RUN.

iMOD is reading the content of the RUN file and starts the 3-D tool.

Note: {installfolder} refers to the full path of the directory you installed iMOD in (e.g. D:\iMOD). Note: If you are a left-handed person and you converted your mouse button settings, ’left mouse button’ should be ’right mouse button’ and vice versa in these tutorials.

Define the Starting Points

Position your Starting Points on the level of the calculated groundwater:

• 4. Make sure the tab ’Pathline’ is active.

• 5. In the upper section ’Start Point Definition’ in the tab ’Pathline’ select the radio-button File.

• 6. Click the Open button and select from {installfolder}\tutorials\TUT_IPS\RESULTS\head\ the file head_steady-state_l1.idf and click the Open button.

• 7. In the activated ’File’ radio-button click the Properties button (   ); the following window will appear:

Flux depending is incorrect here, but means that you can use the positive or negative values on the IDF to start particles. Leave it like this.

• 8. Enter for the XY-Sampling 5 to decrease the number of particles (every 5 cells there will be a starting point).

• 9. Leave the option Vertical Offset that can be used to position particles a bit higher or lower than the selected values in the IDF file.

• 10. The option Randomize places the particles at random locations, activate that option.

• 11. Click Apply.

To add this selection of particles:

• 12. Click the Plus button (   ), you’ll read in the window that 1861 particles are added.

• 13. Click the Glasses button (   ) to display the particles in red. However, you won’t see them yet.

• 14. Go to the tab IDF’s and select the IDF AQUITARD_BOT. Only than you’ll see the particles.

Starting the Particle Tracking

To start the particles simulation follow the next steps:

• 15. Select the tab Pathlines.

• 16. Select the option “Repeat when trapped” , in this way particles are restarted automatically whenever they might be captured by a weak or strong sink.

• 17. Click the Start button.

Pretty nice, isn’t it? You can turn the particle start location on and off by clicking the Glasses button

• 18. Click the Glasses button (   ) on and off.

• 19. You can rotate, zoom and pan during the simulation by the regular mouse functionalities for the 3-D tool, try it!

You can pause the simulation by pressing the Pause button and restart it by clicking the Continue button, so:

• 20. Click the Pause button, notice that you can change all other settings in the 3-D tool as well, just experiment with that.

• 21. Click the Continue button to restart the particle simulation.

Enhance the Appearance

The pathlines are visualized by points or lines, the default is by points, these are the most efficient, howerver, lines sometimes can give a more realistic view, so:

• 22. Click the Lines option.

We can configure the appearance and settings of the current particle set, so:

• 23. Click the Configure Particles… button.

You are now in the Particles Settings window. We alter some settings such as ’Active’, ’Colour’, ’Forward or Backward’, ’Starting Point Size’, ’Pathline Size’ and ’Starting Interval’. In fact it is possible to have different groups of particles that go forward and backward.

• 24. Click the Colour (red) field and change the colour into blue and click OK.

• 25. Increase the size of the line by specifying a 3.0 in P-Size.

• 26. Click Apply.

The appearance of the particles is updated immediately.

Let us add another group of particles.

• 27. Select from the Start Point Definition the option Sink.

• 28. Click the Properties button (   ) associated with this Sink option.

Starting Points around Sinks

Here you can specify how the particles need to be positioned in combination with sinks (a sink is a source that takes water out of the model, such as a river, drain or well). There is a single well in layer 3 that extract 500 m$^{3}$/d, so we would like to put particles around that well, so:

• 29. Enter a value of 5 for Radius, the cell size is 10 meter and we want to have the particles all in the strong sink.

• 30. Enter 10 for Vertical Sampling, so we have 10 intervals in the vertical and 10 per interval on a circle, so in total 10x10=100 particles.

• 31. Click the Apply button.

If the Plus button has been greyed out, that means that there is a simulation active that needs to be stopped first, so:

• 32. Click the Stop button.

• 33. Click the Plus button and notice that 2 groups of particles are now available and in total we have 1961 particles.

• 34. Click the Glasses button to examine the particles.

Change of Particle Tracking Directions

The particle from the well should migrate backwards, so let us change that:

• 35. Click the Configure Particles

• 36. Select the option Backward for the last group. Change the Colour if needed and adapt the P-size.

• 37. Click the Apply button.

• 38. Click the Start button.

The blue particles can be turned off temporarily:

• 39. Click the Configure Particles… button.

• 40. Deactivate the first particles group by un-checking the corresponding box in the ’Act.’-column. Note: The particles settings can be saved from this window using the Save As button, allowing complex particles settings to be re-used.

• 41. Click the Apply button.

42. Click the Stop button to stop the current simulation.

• 43. Click the Start button to start with only the particles from the well.

We can increase the density of the simulation by release more particles after each other, before they actually terminate, so:

• 44. Click the Stop button to stop the current simulation.

• 45. Deselect the option “Repeat when trapped”

• 46. Select the option “Repeat Freq.”

47. Click the Start button.

You see that after a full length of a particle (in this case 10, namely the “tail length” ), another set of particles is released. You can try to see the effect of changing the “Repeat Freq.”

• 48. Click the Spinner ) next to the “Repeat Freq.” input field to see the effect of this. Bigger values will allow more time in between the next particles, as smaller values will release another particle quicker.

Filtering of Particles

The final thing we do it to filter out particles during a simulation.

• 49. Click the Configure Particles… button.

• 50. Deselect the second particles group.

• 51. Select the first set of particles again.

52. Click the Apply button.

• 53. Deselect the option “Repeat Freq.”.

• 54. Select the “Repeat when trapped” again.

55. Click the “Filter part. whenever captured by” option.

• 56. Select the option “Strong Sink”.

• 57. Click the Start button to start the simulation.

Now, only the particles that are captured by a strong sink will be repeated. In this way a sense of a capture zone if created. Okay. That it for today, so close the IPS by:

• 58. Selecting the option “File” from the main menu and than “Quite 3D Tool.”.