Note that this phenomenon has a purely inertial character; viscous forces cannot prevent it, although these forces guarantee the space regularity of the solution.
For small values of s the viscous stresses on the near wall dominate and produce a thrust in the positivex direction.
As the industrial process involves large shear stresses, fibres will slip over one another, and we assume the material to be an anisotropic viscous continuum.
Ultimately sufficiently high wavenumbers are excited that the viscous forces begin to bite, and the dissipation rate then builds up.
This is equivalent to the assumption that above k, a total dissipation of the turbulent energy takes place due to the viscous forces.
This is done using an energy principle based on equating the viscous flow dissipation with the released surface energy.
They performed an extensive set of experiments studying steady and unsteady viscous jet behaviour.
This is in striking contrast to the familiar downstream growing boundary layer and downstream viscous wake existing when the fluid is homogeneous.
