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1. The Reaction between Mn and Se Layers: The Reaction between Mn and Se Layers

   https://doi.org/10.1002/zaac.201800378  

   Choffel, Marisa A.; Hamann, Danielle M.; Joke, Jordan A.; Cordova, Dmitri Leo; Johnson, David C. (December 2018, Zeitschrift für anorganische und allgemeine Chemie)
2. Viscoplastic boundary layers

   https://doi.org/10.1017/jfm.2016.878  

   Balmforth, N. J.; Craster, R. V.; Hewitt, D. R.; Hormozi, S.; Maleki, A. (February 2017, Journal of Fluid Mechanics)

   In the limit of a large yield stress, or equivalently at the initiation of motion, viscoplastic flows can develop narrow boundary layers that provide either surfaces of failure between rigid plugs, the lubrication between a plugged flow and a wall or buffers for regions of predominantly plastic deformation. Oldroyd ( Proc. Camb. Phil. Soc. , vol. 43, 1947, pp. 383–395) presented the first theoretical discussion of these viscoplastic boundary layers, offering an asymptotic reduction of the governing equations and a discussion of some model flow problems. However, the complicated nonlinear form of Oldroyd’s boundary-layer equations has evidently precluded further discussion of them. In the current paper, we revisit Oldroyd’s viscoplastic boundary-layer analysis and his canonical examples of a jet-like intrusion and flow past a thin plate. We also consider flow down channels with either sudden expansions or wavy walls. In all these examples, we verify that viscoplastic boundary layers form as envisioned by Oldroyd. For each example, we extract the dependence of the boundary-layer thickness and flow profiles on the dimensionless yield-stress parameter (Bingham number). We find that, while Oldroyd’s boundary-layer theory applies to free viscoplastic shear layers, it does not apply when the boundary layer is adjacent to a wall, as has been observed previously for two-dimensional flow around circular obstructions. Instead, the boundary-layer thickness scales in a different fashion with the Bingham number, as suggested by classical solutions for plane-parallel flows, lubrication theory and, for flow around a plate, by Piau ( J. Non-Newtonian Fluid Mech. , vol. 102, 2002, pp. 193–218); we rationalize this second scaling and provide an alternative boundary-layer theory. 

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3. Prograde vortices, internal shear layers and the Taylor microscale in high-Reynolds-number turbulent boundary layers

   https://doi.org/10.1017/jfm.2021.478  

   Heisel, Michael; de Silva, Charitha M.; Hutchins, Nicholas; Marusic, Ivan; Guala, Michele (August 2021, Journal of Fluid Mechanics)

   null (Ed.)

   The statistical properties of prograde spanwise vortex cores and internal shear layers (ISLs) are evaluated for a series of high-Reynolds-number turbulent boundary layers. The considered flows span a wide range of both Reynolds number and surface roughness. In each case, the largest spanwise vortex cores in the outer layer of the boundary layer have size comparable to the Taylor microscale $$\lambda _T$$ , and the azimuthal velocity of these large vortex cores is governed by the friction velocity $${u_\tau }$$ . The same scaling parameters describe the average thickness and velocity difference across the ISLs. The results demonstrate the importance of the local large-eddy turnover time in determining the strain rate confining the size of the vortex cores and shear layers. The relevance of the turnover time, and more generally the Taylor microscale, can be explained by a stretching mechanism involving the mutual interaction of coherent velocity structures such as uniform momentum zones with the evolving shear layers separating the structures. 

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4. Stable Boundary Layers and Subfilter-Scale Motions

   https://doi.org/10.3390/atmos14071107  

   McWilliams, James C; Meneveau, Charles; Patton, Edward G; Sullivan, Peter P (July 2023, Atmosphere)

   Recent high-resolution large-eddy simulations (LES) of a stable atmospheric boundary layer (SBL) with mesh sizes N=(5123,10243,20483) or mesh spacings ▵=(0.78,0.39,0.2) m are analyzed. The LES solutions are judged to be converged based on the good collapse of vertical profiles of mean winds, temperature, and low-order turbulence moments, i.e., fluxes and variances, with increasing N. The largest discrepancy is in the stably stratified region above the low-level jet. Subfilter-scale (SFS) motions are extracted from the LES with N=20483 and are compared to sonic anemometer fields from the horizontal array turbulence study (HATS) and its sequel over the ocean (OHATS). The results from the simulation and observations are compared using the dimensionless resolution ratio Λw/▵f where ▵f is the filter width and Λw is a characteristic scale of the energy-containing eddies in vertical velocity. The SFS motions from the observations and LES span the ranges 0.1<Λw/▵f<20 and are in good agreement. The small, medium, and large range of Λw/▵f correspond to Reynolds-averaged Navier–Stokes (RANS), the gray zone (a.k.a. “Terra Incognita”), and fine-resolution LES. The gray zone cuts across the peak in the energy spectrum and then flux parameterizations need to be adaptive and account for partially resolved flux but also “stochastic” flux fluctuations that represent the turbulent correlation between the fluctuating rate of strain and SFS flux tensors. LES data with mesh 20483 will be made available to the research community through the web and tools provided by the Johns Hopkins University Turbulence Database. 

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5. Predicting and Synthesizing Interface Stabilized 2D Layers

   https://doi.org/10.1021/acs.chemmater.1c01064  

   Hamann, Danielle M.; Rudin, Sven P.; Asaba, Tomoya; Ronning, Filip; Cordova, Dmitri Leo; Lu, Ping; Johnson, David C. (July 2021, Chemistry of Materials)