An experimental and theoretical investigation is reported
on the asymmetric, quasi-parallel flow of turbulent incompressible
fluids.
The experimental programme consisted of providing detailed
measurements of mean and turbulent characteristics of the
fully developed flow in a plane channel having one smooth
wall, while the other was roughened by transverse square ribs.
The dissimilar wall conditions imposed a strong asymmetry upon
both mean and turbulent flow fields bringing into prominance
several interating features that are concealed in the symmetric
flow situations.
The theoretical investigation concerned the provision of
a procedure capably of accurate prediction of strongly asymmetric
quasi-parallel flows. The research was concentrated upon the
physical aspect of the problem, that is the establishment and
testing of an approximate closed set of the transport equations,
sufficient for the accurate description of the considered flows.
Two physical models have been explored, both of which used the
Spalding-Patankar numerical method for the solution of resulting
equations. The first model, based upon the extension of Kolmogaa
Prandtl eddy viscosity formula was tested in plane all-smooth
and smooth-rough channels. It showed several deficiencies and
was subsequently discarded.
A second model was established that is described by a
closed set of four partial differential equations for conservation
of mean momentum, turbulent shear stress, turbulent kinetic
energy and its clissipation. This model was extensively tested is several types of duct flows, wall boundary layers and
quasi-parallel free flows. With a single set of empirical
constants, the model yielded predictions of various flow
properties which were in good agreement with experiments.