scholarly journals Non-Newtonian two-phase thin-film problem: Local existence, uniqueness, and stability

Author(s):  
Oliver Assenmacher ◽  
Gabriele Bruell ◽  
Christina Lienstromberg
Keyword(s):  
1982 ◽  
Vol 53 (4) ◽  
pp. 3019-3023 ◽  
Author(s):  
S. N. G. Chu

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 759
Author(s):  
Luana Mazzarella ◽  
Anna Morales-Vilches ◽  
Lars Korte ◽  
Rutger Schlatmann ◽  
Bernd Stannowski

Doped hydrogenated nanocrystalline (nc-Si:H) and silicon oxide (nc-SiOx:H) materials grown by plasma-enhanced chemical vapor deposition have favourable optoelectronic properties originated from their two-phase structure. This unique combination of qualities, initially, led to the development of thin-film Si solar cells allowing the fabrication of multijunction devices by tailoring the material bandgap. Furthermore, nanocrystalline silicon films can offer a better carrier transport and field-effect passivation than amorphous Si layers could do, and this can improve the carrier selectivity in silicon heterojunction (SHJ) solar cells. The reduced parasitic absorption, due to the lower absorption coefficient of nc-SiOx:H films in the relevant spectral range, leads to potential gain in short circuit current. In this work, we report on development and applications of hydrogenated nanocrystalline silicon oxide (nc-SiOx:H) from material to device level. We address the potential benefits and the challenges for a successful integration in SHJ solar cells. Finally, we prove that nc-SiOx:H demonstrated clear advantages for maximizing the infrared response of c-Si bottom cells in combination with perovskite top cells.


Author(s):  
Hsin-Sen Chu ◽  
Shih-Ming Chang

This study presents a transient, one-dimensional, and two phase model of the proton exchange membrane fuel cell cathode. A thin film-agglomerate approach is applied to the catalyst layer. The model includes the transport of gaseous species, liquid water, proton, and electrochemical kinetics. The effect of water flooding both in the gas diffusion layer and catalyst layer in the cathode are investigated. The effects of agglomerate radius and the catalyst layer thickness on the overall cell performance are also investigated. The results show that the time for fuel cells to reach the steady state is in the order of 10 sec due to the effect of water accumulated both in the porous layer and the membrane. However the time for proton transport is in the order of 0.1 sec. In addition, before the ionic potential reaches the steady state, it would get a critical value. The critical value would depend on the operating cell voltage. There seems to be an optimum in the catalyst layer thickness and agglomerate radius.


2019 ◽  
Vol 16 (04) ◽  
pp. 701-742 ◽  
Author(s):  
Xiaopeng Zhao

We study the density-dependent incompressible Cahn–Hilliard–Navier–Stokes system, which describes a two-phase flow of two incompressible fluids with different densities. We establish the local existence and uniqueness of strong solutions to the initial value problem in a bounded domain, when the initial density function enjoys a positive lower bound.


Author(s):  
Sheng Wang ◽  
Junxiang Shi ◽  
Hsiu-Hung Chen ◽  
Tiancheng Xu ◽  
Chung-Lung (C. L.) Chen

With the inspiration from electrowetting-controlled droplets, the potential advantages of electrowetting for bubble dynamics are investigated experimentally and numerically. In our experimental system, a 100 nanometer thin film gold metal was used as an electrode, and a 6.5 micrometer polydimethylsiloxane (PDMS) was spin-coated on the electrode acting both as an dielectric layer and hydrophobic surface. A two-phase model coupled with a electrostatics was used in our simulation work, where the body force due to the electric field acts as an external force. Our numerical results demonstrated that electrowetting can help the detachment of a small bubble by changing the apparent contact angle. Similar results were observed in our experiments that with electrowetting on dielectric, the contact angle of bubble on a hydrophobic surface will obviously decrease when a certain electrical field is applied either with a small size bubble (diameter around 1mm) or a relatively larger size bubble (diameter around 3 mm). When the applied voltage becomes high enough, both the experimental and numerical results demonstrate the characteristics of bubble detachment within a thin film liquid layer.


Author(s):  
Ram Ranjan ◽  
Abhijeet Patel ◽  
Suresh V. Garimella ◽  
Jayathi Y. Murthy

The thermal and hydrodynamic performance of passive two-phase cooling devices such as heat pipes and vapor chambers is limited by the capabilities of the capillary wick structures employed. The desired characteristics of wick microstructures are high permeability, high wicking capability and large extended meniscus area that sustains thin-film evaporation. Choices of scale and porosity of wick structures lead to tradeoffs between the desired characteristics. In the present work, models are developed to predict the capillary pressure, permeability and thin-film evaporation rates of various micropillared geometries. Novel wicking geometries such as conical and pyramidal pillars on a surface are proposed which provide high permeability, good thermal contact with the substrate and large thin-film evaporation rates. A comparison between three different micropillared geometries — cylindrical, conical and pyramidal — is presented and compared to the performance of conventional sintered particle wicks. The present work demonstrates a basis for reverse-engineering wick microstructures that can provide superior performance in phase-change cooling devices.


Author(s):  
Hemanth K. Dhavaleswarapu ◽  
Suresh V. Garimella ◽  
Jayathi Y. Murthy

Thin-film evaporation from a meniscus in a confined space, which is the basis for many two-phase cooling devices, is experimentally investigated. The meniscus formed by heptane, a highly wetting liquid, on a heated, fused quartz substrate is studied. Microscale infrared temperature measurements performed near the thin-film region of the evaporating meniscus reveal the temperature suppression caused by the intensive evaporation in this region. The high spatial resolution (∼6.3 μm) and high temperature sensitivity (∼20 mK) of the infrared camera allowed for accurate measurements. The effects of meniscus thickness and applied heat flux on the thin-film heat transfer distribution and rate are also explored.


2002 ◽  
Vol 360 (1-2) ◽  
pp. 85-90 ◽  
Author(s):  
A Henningsson ◽  
M.P Andersson ◽  
P Uvdal ◽  
H Siegbahn ◽  
A Sandell

2021 ◽  
Author(s):  
L. N. Maskaeva ◽  
I. V. Vaganova ◽  
V. F. Markov ◽  
V. I. Voronin ◽  
O. A. Lipina ◽  
...  

Abstract The possibility of forming thin-film two-phase compositions CdxPb1-xS/Cd1-dS by using the chemical bath deposition from aqueous media with adding various cadmium salts has been demonstrated. The crystal structure, chemical composition, morphology, and the band gap were studied by the X-ray diffraction, scanning electron microscopy, elemental analysis, Auger and Raman spectroscopy, and diffuse reflectance measurements. The formation of a CdxPb1-xS/Cd1-dS substitutional solid solution phase in well-faceted crystallites on the substrate of an X-ray amorphous CdS phase has been experimentally proved. The found differences in their composition are the result of the effect of the nucleophilicity of the anionic component of the cadmium salt on the kinetics of thiourea decomposition. The results demonstrate the possibility of forming thin-film two-phase compositions or heterostructures on the base of cadmium and lead sulfides in one technological stage by using chemical bath deposition, which can be important for the creation of solar cells.


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