Irrotationality
Irrotationality is a concept primarily used in fluid dynamics and solid mechanics to describe the motion of a body or fluid. A flow or motion is considered irrotational if it lacks angular acceleration. This means that any small fluid parcel or material element within the flow does not rotate with respect to its center of mass. Mathematically, this is often expressed by stating that the curl of the velocity field is zero.
In a purely irrotational flow, there are no vortices or swirling motions. Imagine a fluid flowing through
Conversely, rotational flow or motion involves angular acceleration, leading to the formation of vortices or shear.