scholarly journals Potential Investigation on Multiphase Flow of Loaded Dispersion for the Production of Metallized Paper

2021 ◽  
Vol 58 (1) ◽  
pp. 1-16
Author(s):  
Saadat Ullah Khan Suri ◽  
Mohammad Siddique
Keyword(s):  
Numerical Methods ◽  
Large Eddy Simulation ◽  
Multilayer Coating ◽  
Air Entrainment ◽  
Discrete Element ◽  
Point Particle ◽  
Coarse Grained ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Curtain Coating

The current review research's main objective is to develop dispersion models in the multilayer curtain coating with the production of metallized paper. To achieve this, the curtain coating on the paper substrate is employed with respect to multilayer coating of polymers. The first layer of polymer is applied to the paper and then it is subjected to vacuum metallization with aluminum deposition. After it, another second layer of polymer is subjected on it to prevent it from oxidation. These coated polymers are different in nature. The metallized paper will be produced which has high strength will be formulated in this application of curtain coating. The instability of curtain and air entrainment will be minimized from high Weber number, low Reynolds number, Optimum web speed and Coat weights. The above demonstrated process simulation will be modelled in Ansys-CFD. The dispersion of solids in the curtain flow through substrate moving on the web will be evaluated from different numerical methods. Each method has its own characteristics to study the nature of solids dispersion. The high loaded solids dispersion will be investigated from numerical methods including Langrangian Point Particle, Coarse grained molecular dynamics, Stokesian Dynamics, Brownian Dynamics, Point Particle Method Reynolds Averaged Navier Stokes equation, Eulerian Method, Langrangian-Eulerian Point Particle, Large Eddy Simulation point particle, Combined discrete element and Large Eddy Simulation and Discrete Element Methods.

Large Eddy Simulation of Air Entrainment and Mixing in Reacting and Non-Reacting Diesel Sprays

2014 ◽  
Vol 93 (3) ◽  
pp. 385-404 ◽  
Author(s):  
Cheng Gong ◽  
Mehdi Jangi ◽  
Tommaso Lucchini ◽  
Gianluca D’Errico ◽  
Xue-Song Bai
Keyword(s):  
Large Eddy Simulation ◽  
Air Entrainment ◽  
Diesel Sprays ◽  
Eddy Simulation ◽  
Large Eddy

scholarly journals Cooling of Entrained Parcels in a Large-Eddy Simulation

2012 ◽  
Vol 69 (3) ◽  
pp. 1118-1136 ◽  
Author(s):  
Takanobu Yamaguchi ◽  
David A Randall
Keyword(s):  
Large Eddy Simulation ◽  
Inversion Layer ◽  
Longwave Radiation ◽  
Air Entrainment ◽  
Radiative Cooling ◽  
Grid Spacing ◽  
Large Eddy Simulation Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Tracking Model

Abstract The relative importance, for cloud-top entrainment, of the cooling rates due to longwave radiation, evaporation, and mixing was assessed through analysis of the results produced by a Lagrangian parcel-tracking model (LPTM) incorporated into a large-eddy simulation model. The LPTM predicts each parcel’s trajectory over time, using the resolved velocity simulated by the host model. An LPTM makes it possible to identify entrained parcels; this is almost impossible to do in an observational study. A nocturnal stratocumulus cloud was simulated over 4h using a 5-m horizontal grid spacing and a 2.5-m vertical grid spacing. At the start of the last hour of the simulation, over 40 million parcels were placed near the top of the inversion layer and then tracked. Parcel histories were analyzed to identify entrained parcels. Entrainment occurs in cloud holes, which occur in dry regions of sinking air. Entrainment into the mixed layer is regulated by buoyancy, which requires parcels to be precooled in the inversion layer, prior to entrainment. A mixing fraction analysis was used to separate the cooling due to longwave radiation, evaporation, and mixing. Results show that radiative and evaporative cooling are of comparable importance, but that mixing is by far the dominant cooling mechanism. The radiative cooling rate is strongly inhomogeneous, and only weak radiative cooling is found in regions of entrainment. Therefore, the entrained parcels experience less than the horizontal-mean radiative cooling. Although radiative cooling maintains the boundary layer turbulence, its direct effect on buoyancy of entrained parcels is modest.

Large-Eddy Simulation for the Roughness Sublayers over Real Urban Surfaces 

2021 ◽  
Author(s):  
Lan Yao ◽  
Chun-Ho Liu
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Momentum Flux ◽  
Local Maximum ◽  
Air Entrainment ◽  
Urban Morphology ◽  
Conditional Sampling ◽  
Law Of The Wall ◽  
Eddy Simulation ◽  
Large Eddy

<p><strong>ABSTRACT: </strong></p><p>    With the continuous spreading of global pandemic, environmental issues have aroused worldwide unprecedented attention. Airflow plays a crucial role in aerosol motions and pollutants removal in dense cities. Large-eddy simulation (LES) is conducted for a typical metropolitan, Hong Kong, to investigate the dynamics in the atmospheric boundary layer (ABL) over real urban surfaces. Full-scale building models (average building height h<sub>m</sub> = 36 m) from Tsim Sha Tsui to Sham Shui Po, Kowloon Peninsula, are digitalized. Southerly wind with speed U<sub>∞</sub> (= 10 m sec<sup>-1</sup>) in neutral stratification is prescribed at the domain inlet. The turbulence statistics extracted from three subdomains in Mong Kok neighborhood, each with size 800 m (streamwise) × 100 m (spanwise) × 500 m (vertical), are analyzed. Linear regression of the wind profile with the logarithmic law of the wall (log-law) show that the interface between inertial sublayer (ISL) and roughness sublayer (RSL) is in the range of 2.5h<sub>m</sub> to 4.5h<sub>m</sub>. In the RSL, the streamwise and vertical velocities are positively (S<sub>u</sub> > 0) and negatively (S<sub>w</sub> < 0) skewed, respectively. Their kurtosis K<sub>u</sub> and K<sub>w</sub> is less than 3. Conditional sampling of vertical momentum, flux u’’w’’ showed that ejection Q2 occurs more frequently than does sweep Q4. On the contrary, the contribution of Q4 exceeds that of Q2. These characteristics switch to the other way round in the ISL. Furthermore, the difference between Q4 and Q2, either in terms of occurrence or contribution, shows a local maximum around 50% of the total momentum flux, suggesting the major energy-carrying scales. Coherent structures depict elongated, (massive,) accelerating (decelerating) and descending (ascending) RSL (ISL) flows. Hence, the fresh (aged) air entrainment (detrainment) are signified by fast and extreme (slow and frequent) flows. These distinct features of RSL flows over real urban morphology provide an inspiration to improve the ground-level air quality by proper urban planning.</p><p><strong>KEYWORDS:</strong> Large-eddy simulation (LES), real urban morphology, turbulent boundary layer (TBL), conditional sampling, hole filtering</p><p> </p><p> </p>

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