An incompressible flow is described by a velocity field which is solenoidal.

For the special (but very common) case of incompressible flow, the momentum equations simplify significantly.

For incompressible flow, the divergence of the volume flux is zero.

This means that - unlike incompressible flow - changes in density must be considered.

Note that this is not the same as an incompressible flow, for which the barotropic term cannot be neglected.

This is an idealization, which leads to the theory of incompressible flow.

Many authors define dynamic pressure only for incompressible flows.

In general, equation (2) is applicable only for incompressible flows.

Note that only the convective terms are nonlinear for incompressible Newtonian flow.

In this case the flow can be modeled as an incompressible flow.