# Wiki

# D2D Software / How to implement washing and bolus injection

Similar to the bolus injection example, sometimes a washing event should be modeled.

Such event can be modeled by an additional input function:

INPUTS Washing C nM conc. "wash_strength * (1/sqrt(2*pi*wash_duration^2)) * exp(-(t - wash_timepoint)^2/(2*wash_duration^2))"

The function is a scaled normal distribution (given that `t`

indicates the independent variable) with area under the curve given by the value of `wash_strength`

and should be choosen large enough. The washing time point is given by `wash_timepoint`

and the duration by `wash_duration`

.

Additionally, one has to specify a reaction that removes the respective state variable (here `Ligand`

) proportional to the `Washing`

signal:

REACTIONS Ligand -> CUSTOM "Ligand * Washing"

In the folder `/Examples`

we provide some showcase applications `Washing_and_Injection_Test`

that can be used as a starting point for a new modeling project.

In this example a first bolus of 5 nM is injected at time point 30 minutes over a period of 1 minute. At time point 50 minutes `Ligand`

is washed almost completely, and at time point 60 minutes another bolus of 3 nM is injected.

Updated