On this page you define how your particles appear. Colour, diameter and stuff like that. You can also choose whether your particles should be randomly or uniformly distributed over the area. If you want to place a single particle in the area, and calculate the trajectory, please use the “Track Flow Visualisation” plot, also provided with the Plot Composer.
The length of the particle defines how you see the trajectory behind the moving particle. If you define the length to be 6, you will se a tail of 6 particles, faded out at the end.
The particle density per unit is calculated as follows: During the simulation, the area is split up in smaller cells. The number of particles is counted within these cells. If the number of particles in a particular cell becomes smaller or larger than the minimum or maximum specified, particles will be added or removed.