Abstract:
The thesis describes a computational investigation of turbulent boundary layer in
transition from smooth to rough surface. The scope of the present computational
study is limited to numerical prediction of the flow parameters of steady two
dimensional turbulent flow over smooth to rough surface at different Reynolds
numbers. "TEACH-T", a general computer programme has been used for this
purpose.
The governing partial differential equations expressed in cartesian co-ordinate
system are discretised in a finite difference technique. A staggered arrangement
of variables has been used in conjunction with the SIMPLE algorithm. The upwind
differencing scheme is employed to evaluate the convective terms.
The time averaged governing equations of mean flow is closed using the standard
k-e turbulence model.
The surface texture of the rough portion used in experiment is simulated in the
present computation in two different ways (i) Mean height type: computational
cells of total height equal to the height of the average stone chips used in the
experiment are continuously blocked off to incorporate the rough surface into t.he
flow domain. (ii) Saw tooth type: computational cells are blocked off in such a way
that the blocked cells give the bottom surface a saw tooth type configurat.ion with
the saw tooth height equal to the average stone chips height.
The prediction is in good agreement with the experimental data in the smooth
surface. Whereas, in the rough surface: for mean height type; the velocity profiles
conform with the experimental data but pressure gradient is under predicted, for
saw tooth type; pressure gradient conform with the experimental data but velocity
profile is under predicted .
