The Initial Values node specified the initial values for the number densities of the different size intervals. These are used as an initial guess for a stationary solver or as initial conditions for a transient simulation.

Select either User defined or Define individually from the list. When User defined is selected, enter a value or expression for the initial value of the number density to be used for all size intervals. When User defined is selected, the text field also accepts an expression written as a function of the particle size, pop.L. Instead, when Define individually is selected, a number density can be entered for each dependent variable individually with the unit 1/m4. To instead specify number densities independent of interval length, select Define number densities independent of interval length. The number densities then have the unit 1/m3.