Let's consider how to generate forcing inputs. If we have a tank, the input could be changed from one inlet pipe to another by quickly opening one valve and closing the other. A step would result from one switch or a pulse would result from switching back to the original conditions. An alternative would be to dump concentrated material directly into the tank; this method of step-up is convenient. Even with intense mixing, several seconds could elapse before the concentration becomes uniform at the new level after forcing in a large vessel. When the mixing is poor, the concentration profiles tend to be very complicated.
Responses to Forcing Forcing Functions for Microorganisms