A mud agitator is mainly used to agitate and mix the drilling mud to prevent solid particles from depositing in the tank. For proper mixing the mud agitator must be properly sized with respect to power requirement and impeller size.
Flow simulation (CFD) can be used to predict the rate of deposition in a tank. In many cases CFD is convenient for purposes of preliminary assessment, when the only opportunity to perform physical test is after the agitator is already installed in the field. Simulation can also be used efficiently to optimize with respect to engine power and impeller design.
The most accurate approach is to model the deposition in the tank as time passes. This is called a transient simulation. However, transient simulationis are very time consuming. A faster approach is to assume steady-state condition of the circulating fluid. For mud agitators this is usually a very good approximation to assume that the flow is not changing with time.
A normal measure of the degree of circulation is the turnover rate (TUR). This is a measure of the number of turns/circuits a reference volume of particles completes in the tank during a given time. The circuit is shown in the figure below.