Turbulent mixing of two parallel similar and dissimilar fluid streams, comparing velocity and density profiles measurements with similarity solution

This study considers the analysis of the developing flow due to the mixing of two uniform incompressible fluid streams with different velocities. Using the method of matched asymptotic expansions, solutions valid in three regions of the free shear layer are obtained. The expansion process uses a small parameter based on the difference between free‐stream velocities and, unlike previous studies, is applied to the complete Navier–Stokes equations. The controversy involving the choice of a proper third boundary condition for the free shear layer between parallel streams is avoided in the present approach. This is achieved by matching the downstream solutions, valid inside and outside the mixing layer, to the solution describing the flow in the initial mixing region near the start of mixing. Results of the analysis indicate that the transverse velocity, in the developing free shear layer between two uniform streams, approaches similarity at a much slower rate than the longitudinal velocity. The analysis also showed that, in the early stages of the mixing process between two uniform streams, the faster stream is initially displaced away from the shear layer. This initial flow displacement is not predicted by the downstream mixing‐layer similarity solution.

Turbulent Mixing of Two Parallel Streams—Part 2: An Experimental Investigation

Citations

Decay of a laminar shear layer

Two-Stream Heterogeneous Mixing Measurements Using Laser Doppler Velocimeter

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