### 10.2.1. Setup

Mixing vessels generally use two domains. The impeller domain is a small, rotating domain that encloses the impeller. The rest of the tank is represented by a stationary domain. Different types of domain interfaces are available for the connection between the stationary and the rotating domains. The recommended types are:

- Frozen Rotor: faster but cruder

- Transient: slower (transient analysis) but much more accurate

The choice of a steady-state or transient simulation is dependent on the type of interface that exists between the two domains. Where a Frozen Rotor interface is used, a steady-state simulation is usually carried out. Performing a transient simulation allows you to use the transient rotor/stator frame change model to account for transient effects.

The initial guess for velocity can be set to zero in the relative frame for each domain.

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