# Replace mechanical interaction force¶

Author: Lukas Breitwieser
This tutorial demonstrates how to replace BioDynaMo's default interaction force with a user-defined one. The interaction force is used to calculate forces between agent pairs that are in physical contact with each other.

Let's start by setting up BioDynaMo notebooks.

We modify the simulation_max_displacement parameter to better visualize the difference of the user-defined force that we will add.

In our experiment we create two overlapping cells and visualize the starting condition.

Let's run our experiment and have a look at the visualization.

We continue by simulating 10 iterations and observe how the mechanical force pushed the two cells away from each other, until they don't overlap anymore.