The performance of a bioreactor is driven by how well the reactants get mixed and converted into the final product. The shape of the tank, the position and shape of the impellers and baffles, as well as the impeller rotational speed, affect how the mixture would move inside the tank. Different flow particles would follow different paths and spend a different amount of time inside the bioreactor, and therefore the reactants would either have more, or less time to react and convert into the final product. The time that a fluid particle spends inside the tank is defined as the residence time. The residence time distribution (RTD) is an important parameter that helps engineers understand how well a reactor design would perform compared to an ideal reactor.
In this lesson we will learn how to set up and perform an unsteady simulation and track in time the concentration of a tracer at the outlet. The data collected from this simulation would be essential to estimate the residence time distribution. For setting up the transient simulation, you can either use the files from the previous lesson or start with the files provided here.