On common exact solutions of Navier-Stokes and quasi-hydrodynamic systems for nonstationary flows

It is shown that the Trkal method for constructing uniformly-helical solutions of nonstationary Navier-Stokes equations is applicable for quasi-hydrodynamic system. A wider class of flows, obeying the generalized Gromeki-Beltrami condition, is considered. Examples of exact solutions, common to the Navier-Stokes and quasi-hydrodynamic systems, but not satisfying the Euler equations, are given.