Investigation of reattachment length for a turbulent flow over a backward facing step for different step angle

Abstract

Computational investigations are carried out on flow through a channel having a single backward facing step. The effect ofstep angle and expansion ratio on separation length is studied and compared with experimental results reported in literature. Thestep angles considered are 15°, 30°, 45° and 90°, whereas the expansion ratios considered are 1.48 and 2.0. A two-dimensional(2D), segregated, renormalized group (RNG) k.å turbulence model has been chosen for CFD simulations. The analysis of the results showed that with the increase in step angle and expansion ratio, the reattachment length increases. Effect of Reynolds number is also studied by varying it over a range 15000 to 64000 and it also shows that the reattachment length increases with an increase of the Reynolds number.