Question

Difference between inviscid and viscous liquid equation of motion

Answer 1

Fluid flows are commonly divided into two broad categories—namely, inviscid and viscous flows. This chapter describes the fundamentals of viscous flows and turbulence along with the associated theory. These flows are widely used in micrometeorology and fluid mechanics. All viscous flows can broadly be classified as laminar and turbulent flows, although an intermediate category of transition between the two has also been recognized. A laminar flow is characterized by smooth, orderly, and slow motion in which adjacent layers of fluid slide past each other with very little mixing and the transfer of properties across the layers. In laminar flows, the flow field and the associated temperature and concentration fields are regular and predictable and vary only gradually in space and time. Turbulent flows are highly irregular, almost random, three-dimensional, highly rotational, dissipative, and have very diffusive (mixing) motions. In these, all the flow and scalar properties exhibit highly irregular variations in both time and space, with a wide range of temporal and spatial scales. The simplest viscous flows are the steady, one-dimensional, laminar flows between two infinite parallel planes. Because velocity varies only normal to the planes and there is no motion across the planes, the inertia terms in the Navier–Stokes equations are zero.