Experiments in Fluids

, Volume 34, Issue 2, pp 220–226 | Cite as

Plane mixing layers from parallel and non-parallel merging of two streams

  • M. Abdul AzimEmail author
  • A. K. M. Sadrul Islam


Two types of mixing layers produced from two streams merging at 0° and 18° have been investigated. Each type of mixing layer was produced with velocity ratios 0.7, 0.8 and 0.9 and measurements were taken at six streamwise locations. The boundary layers were untripped and initially turbulent in all cases. Both types of mixing layers were found to attain a self-similar state for velocity ratios 0.7 and 0.8 but failed for 0.9 within the measurement domain. It appears that the mixing layer flow becomes self-similar earlier when merging at 18° than at 0°. With increasing velocity ratio, the development distance was increased and the splitter wake played a dominant role in the development of the mixing layers. The mixing layers from non-parallel merging streams (18°) were found to have higher growth in the near-field than those from parallel merging streams (0°). Both types of mixing layers were found to decrease in growth with increasing velocity ratio, though they spread more at the high-speed side.


Reynolds Stress Velocity Ratio Free Shear Layer Streamwise Pressure Gradient Streamwise Velocity Profile 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols


angle of merging


mixing layer thickness (=y 0.1y 0.9)


similarity variable [=(yy 0.5)/δ]


modified velocity ratio [=(1−r)/(1+r)]


velocity ratio (=u 2/u 1)


Reynolds number based on θ (=u o θ/ν)


momentum thickness of the mixing layer


mean velocities in x and y directions, respectively


fluctuating component of the streamwise velocity


non-dimensional velocity [=(uu 2)/(u 1u 2)]


mixing layer convection velocity [=(u 1+u 2)/2]


free-stream velocity (at 470 mm upstream)


shear velocity (=u 1u 2)


mean velocities of high and low speed streams, respectively

\(\overline {u'^2 } \)

Reynolds streamwise normal stress

\(\overline {v'^2 } \)

Reynolds cross-stream normal stress

\(\overline {w'^2 } \)

Reynolds spanwise normal stress

\(\overline {u'v'} \)

Reynolds primary shear stress

x, y

streamwise and cross-stream directions, respectively


virtual origin of the mixing layer


isovel for u =0.1; similarly for y 0.05, y 0.5, y 0.9 and y 0.95


max maximum value at given x location


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Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringBangladesh University of Engineering and TechnologyDhakaBangladesh

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