

Article
Drag reduction in spatially developing turbulent boundary layers by blowing at constant massflux
Authors: 
Kametani, K., Fukagata, K., Örlü, R., Schlatter, P. 
Document Type: 
Conference 
Pubstate: 
Published 
Journal: 
Proc. 9th Turbulence Shear Flow Phenomena (TSFP9), June 30  July 3, 2015, The University of Melbourne, Australia 
Volume: 
1

Year: 
2015 
AbstractA series of largeeddy simulations of spatially developing turbulent boundary layers with uniform blowing at moderate Reynolds numbers (based on freestream velocity and momentum thickness) up to Re = 2500 were performed with the special focus on the effect of intermittent (separated in streamwise direction) blowing sections. The number of blowing sections, N, investigated is set to be 3, 6, 20, 30 and compared to N = 1, which constitutes the reference case, while the total wallmass flux is constrained to be the same for all considered cases, corresponding to a blowing amplitude of 0.1% of U? for the reference case. Results indicate that the reference case provides a netenergy saving rate of around 18%, which initially decreases at most 2 percentage points for N = 3 but recovers with increasing N. The initial reduction of the drag reduction is due to the shorter streamwise length of intermittent blowing sec tions.The physical decomposition of the skin friction drag through the FIK identity (Fukagata et al., 2002), shows that the distribution of all components over each blowing section has similar trends, resulting in similar averaged values over the whole control region.
http://www.tsfpconference.org/proceedings/2015/v1/1A4.pdf

