Separated flow phenomena over roughened surfaces

Both numerically and experimentally studies of the fluid characteristics of laminar/turbulent flow over surface mounted ribs. The effects of the rib aspect ratios and Reynolds number as well as initial boundary-layer thickness on entire flow field, separated region, and reattachment length were extensively investigated. More than 10 journal papers in this area were published. Two panel discussion of ASME related conferences, were invited.

Laminar fored convection from Surface-mounted ribs

Author
Source
Abstract
SHOU-SHING HSIEH, HUEI-JAN SHIH and YING-JONG HONG
International Journal of Heat and Mass Transfer, Vol.33,No.9,pp.1987-2000,1990
A study for both numerical and experimental aspects on low speed forced convective heat transfer near two-dimensional transverse ribs in which the walls are held at a uniform temperature is presented. The effects of aspect ration and Reynolds number as well as the initial boundary layer thickness are examined and discussed. The numerical technique is based on a power law combined with a false stream function- vorticity form. It is found that the temperature data agree reasonable well with those taken from the experiments qualitatively. The results are further correlated by an equation of the form.

Numerical Computation of Laminar Separation and Reattachment of Flow Over Surface Mounted Ribs

Author
Source
Abstract
YING-JONG HONG , SHOU-SHING HSIEH , HUEI-JAN SHIH
ASME Journal of Fluids Engineering, Vol.113,No.2,1991,pp.190-198
Numerical results are presented concerning the fluid characteristics of steady-state laminar flow over surface mounted ribs. Computations are carried out using a false transient stream function- vorticity form. The effects of the aspect ratios (width-to-depth) of the ribs and Reynolds numbers as well as initial boundary-layer thickness on entire flow field, separated region, and reattachment length are presented and discussed. The computed reattachment distance compares reasonably well with those data reported by previous studies. A correlation is provided in terms of the rib aspect ration, Reynolds number , and the ratio of boundary-layer thickness and rib height. The pressure drop is excessive along the upstream vertical step face and it recovers thereafter, which agrees qualitatively with those of the previous studies for the flow over backward-facing steps.