Study on a Turbulent Boundary Layer with Injection : Turbulent Scales

Abstract

Turbulent integral and differential scales have been measured in a turbulent boundary layer with injection and the effects of injection on these scales are investigated. In the inner layer, the longitudinal integral scale decreases with increasing the injection rate, but the transverse integral scale remains unchanged. On the other hand, both of these scales decrease in the outer layer. The ratio of transverse to longitudinal integral scales increases with increasing the injection rate and approaches a value of 0.5. This result suggests that turbulence tends to be isotropic with injection. The ratio of differential to integral scales becomes greater near the wall with increasing the injection rate, mainly due to the reduction in the turbulent Reynolds number.