Experimental Study Shows Mean Flow Skew Reduces Turbulent Mixing Layer Intensity but Preserves Core Dynamics
Researchers developed and validated an experimental framework to study three-dimensional skewed turbulent mixing layers, finding that introducing spanwise mean-flow skew reduces mean and turbulent quantities by up to approximately 40% compared to standard planar configurations. Despite these quantitative reductions, core mixing layer characteristics—including similarity scaling of velocity profiles, linear shear-layer growth, and near-Gaussian Reynolds-stress profiles—remained largely intact. The findings provide an empirical benchmark for future research into three-dimensional free-shear turbulence, which is common in practical engineering flows but has been far less studied than its two-dimensional counterpart.
A new experimental study published on arXiv investigates how mean-flow skew—where incoming streams are angled rather than parallel—affects turbulent mixing layers, a class of flow relevant to many real-world engineering applications. The researchers introduced skew using turning vanes near the trailing edge of a splitter plate and employed cross-wire anemometry to track the downstream evolution of the flow. Compared to planar (non-skewed) mixing layers, the skewed configuration showed systematic reductions in both mean-flow and turbulent quantities, with deviations reaching roughly 40%. However, fundamental structural characteristics were preserved: velocity profiles still collapsed under similarity scaling, shear-layer thickness continued to grow approximately linearly downstream, and Reynolds-stress profiles retained their near-Gaussian shape. Notably, Townsend's structure parameter—a measure of turbulent momentum transport efficiency—remained approximately invariant between planar and skewed configurations, contrasting with skewed turbulent boundary layers where comparable skewing reduces this parameter by about 30%. The authors conclude that mean-flow skew is a quantitative rather than qualitative modifier of mixing layer dynamics. The study establishes a controlled experimental methodology and empirical dataset intended to serve as a benchmark for future computational and theoretical work on three-dimensional free-shear turbulence.
What's missing
The degree to which findings extend beyond the specific vane geometry and splitter-plate configuration employed is not fully addressed. As a preprint, the work has not yet undergone formal peer review.
What different sources said
- arXiv physicsCenter
Effects of mean flow skew on turbulent shear layers. Part II. Experimental investigation
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