Transition layer thickness in microlaminar deposits

1993 ◽  
Vol 23 (6) ◽  
pp. 662-668 ◽  
Author(s):  
A. R. Despić ◽  
T. LJ. Trišović
Keyword(s):  
Layer Thickness ◽  
Transition Layer

scholarly journals Observations of the Transition Layer

2009 ◽  
Vol 39 (3) ◽  
pp. 780-797 ◽  
Author(s):  
T. M. Shaun Johnston ◽  
Daniel L. Rudnick
Keyword(s):  
Layer Thickness ◽  
Mixed Layer ◽  
Potential Vorticity ◽  
Transition Layer ◽  
Mixed Layer Depth ◽  
Density Ratio ◽  
Horizontal Resolution ◽  
Surface Mixed Layer ◽  
Layer Depth ◽  
Vertical Displacements

Abstract The transition layer is the poorly understood interface between the stratified, weakly turbulent interior and the strongly turbulent surface mixed layer. The transition layer displays elevated thermohaline variance compared to the interior and maxima in current shear, vertical stratification, and potential vorticity. A database of 91 916 km or 25 426 vertical profiles of temperature and salinity from SeaSoar, a towed vehicle, is used to define the transition layer thickness. Acoustic Doppler current measurements are also used, when available. Statistics of the transition layer thickness are compared for 232 straight SeaSoar sections, which range in length from 65 to 1129 km with typical horizontal resolution of ∼4 km and vertical resolution of 8 m. Transition layer thicknesses are calculated in three groups from 1) vertical displacements of the mixed layer base and of interior isopycnals into the mixed layer; 2) the depths below the mixed layer depth of peaks in shear, stratification, and potential vorticity and their widths; and 3) the depths below or above the mixed layer depth of extrema in thermohaline variance, density ratio, and isopycnal slope. From each SeaSoar section, the authors compile either a single value or a median value for each of the above measures. Each definition yields a median transition layer thickness from 8 to 24 m below the mixed layer depth. The only exception is the median depth of the maximum isopycnal slope, which is 37 m above the mixed layer base, but its mode is 15–25 m above the mixed layer base. Although the depths of the stratification, shear, and potential vorticity peaks below the mixed layer are not correlated with the mixed layer depth, the widths of the shear and potential vorticity peaks are. Transition layer thicknesses from displacements and the full width at half maximum of the shear and potential vorticity peak give transition layer thicknesses from 0.11× to 0.22× the mean depth of the mixed layer. From individual profiles, the depth of the shear peak below the stratification peak has a median value of 6 m, which shows that momentum fluxes penetrate farther than buoyancy fluxes. A typical horizontal scale of 5–10 km for the transition layer comes from the product of the isopycnal slope and a transition layer thickness suggesting the importance of submesoscale processes in forming the transition layer. Two possible parameterizations for transition layer thickness are 1) a constant of 11–24 m below the mixed layer depth as found for the shear, stratification, potential vorticity, and thermohaline variance maxima and the density ratio extrema; and 2) a linear function of mixed layer depth as found for isopycnal displacements and the widths of the shear and potential vorticity peaks.

Simulation of Flow Through Variable Permeability Darcy-Brinkman Layers

2021 ◽  
Author(s):  
SamerA Alokaily
Keyword(s):  
Pressure Gradient ◽  
Strain Rate ◽  
Layer Thickness ◽  
Transition Layer ◽  
Darcy Number ◽  
Fluid Viscosity ◽  
Channel Depth ◽  
Clear Fluid ◽  
Variable Permeability ◽  
Permeable Media

Abstract In this paper, coupled parallel flow in a triple layer channel is studied numerically. The channel consists of a clear fluid sandwiched between two Darcy-Brinkman permeable layers of variable porousness. A single binary equation is presented, in which the penetrability within transition porous layers, is portrayed by a nth degree objective capacity. However, because of the absence of explanatory arrangement of the issue, direct numerical simulations are performed in order to give a novel knowledge into the fluid dynamics inside permeable media of variable porousness. These simulations are carried out through utilizing a modified steady state finite volume solver from the open source programming bundle OpenFOAM. After check and approval of the solver and mathematical technique, parametric investigation is acted in which the Darcy number, intensity of the penetrability degree, transition layer thickness, channel depth, fluid viscosity, and pressure gradient vary. The findings of the current study show that velocity increases when: First, the Darcy number, the degree, or the channel depth increases. Second, when the transition layer thickness decreases. Also, strain rate is almost independent of both Darcy number and degree, and nearly doubles when either the thickness of transition layer halves or the channel depth doubles. In addition, velocity and strain rate are found to scale with viscosity and pressure gradient.

Relationship between 4H-SiC∕SiO2 transition layer thickness and mobility

2009 ◽  
Vol 95 (3) ◽  
pp. 032108 ◽  
Author(s):  
T. L. Biggerstaff ◽  
C. L. Reynolds ◽  
T. Zheleva ◽  
A. Lelis ◽  
D. Habersat ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Transition Layer

scholarly journals Transition layer thickness at a fluid-porous interface

2005 ◽  
Vol 17 (5) ◽  
pp. 057102 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Arzhang Khalili ◽  
Bo Barker Jørgensen
Keyword(s):  
Layer Thickness ◽  
Transition Layer ◽  
Porous Interface

scholarly journals Effect of Ti Transition Layer Thickness on the Structure, Mechanical and Adhesion Properties of Ti-DLC Coatings on Aluminum Alloys

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1742 ◽  
Author(s):  
Hongshuai Cao ◽  
Fugang Qi ◽  
Xiaoping Ouyang ◽  
Nie Zhao ◽  
Yun Zhou ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Layer Thickness ◽  
Photoelectron Spectroscopy ◽  
Transition Layer ◽  
Scratch Test ◽  
Vacuum Arc ◽  
Adhesion Properties ◽  
Dlc Coatings ◽  
Dlc Coating ◽  
Filtered Cathodic Vacuum Arc

Multilayers of Ti doped diamond-like carbon (Ti-DLC) coatings were deposited on aluminum alloys by filtered cathodic vacuum arc (FCVA) technology using C2H2 as a reactive gas. The effect of different Ti transition layer thicknesses on the structure, mechanical and adhesion properties of the coatings, was investigated by scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nanoindentation and a scratch tester. The results showed that the Ti transition layer could improve interfacial transition between the coating and the substrate, which was beneficial in obtaining excellent adhesion of the coatings. The Ti transition layer thickness had no significant influence on the composition and structure of the coatings, whereas it affected the distortion of the sp2-C bond angle and length. Nanoindentation and scratch test results indicated that the mechanical and adhesion properties of the Ti-DLC coatings depended on the Ti transition layer thickness. The Ti transition layer proved favorable in decreasing the residual compressive stress of the coating. As the Ti transition layer thickness increased, the hardness value of the coating gradually decreased. However, its elastic modulus and adhesion exhibited an initial decrease followed by an increasing fluctuation. Among them, the Ti-DLC coating with a Ti transition layer thickness of 1.1 μm exhibited superior mechanical properties.

Structure and Orientation of As Precipitates in LT-MBE Grown GaAs

1991 ◽  
Vol 49 ◽  
pp. 900-901 ◽  
Author(s):  
Alain Claverie ◽  
Zuzanna Liliental-Weber
Keyword(s):  
Transport Properties ◽  
Layer Thickness ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Lattice Parameter ◽  
Crystalline Quality ◽  
Insulating Properties ◽  
Lt Gaas

GaAs layers grown by MBE at low temperatures (in the 200°C range, LT-GaAs) have been reported to have very interesting electronic and transport properties. Previous studies have shown that, before annealing, the crystalline quality of the layers is related to the growth temperature. Lowering the temperature or increasing the layer thickness generally results in some columnar polycrystalline growth. For the best “temperature-thickness” combinations, the layers may be very As rich (up to 1.25%) resulting in an up to 0.15% increase of the lattice parameter, consistent with the excess As. Only after annealing are the technologically important semi-insulating properties of these layers observed. When annealed in As atmosphere at about 600°C a decrease of the lattice parameter to the substrate value is observed. TEM studies show formation of precipitates which are supposed to be As related since the average As concentration remains almost unchanged upon annealing.

Sign in / Sign up

Export Citation Format

Share Document