Numerical Simulations of the Formation of Melting-Layer Cloud

2008 ◽  
Vol 136 (1) ◽  
pp. 223-241 ◽  
Author(s):  
Kazuaki Yasunaga ◽  
Akihiro Hashimoto ◽  
Masanori Yoshizaki
Keyword(s):  
Numerical Simulations ◽  
Temperature Profile ◽  
Initial Temperature ◽  
Critical Role ◽  
Middle Level ◽  
Squall Line ◽  
Two Dimensional ◽  
Stable Layer ◽  
Cloud Coverage ◽  
Thin Cloud

Abstract A number of previously published observational studies have reported the common occurrence of cloudy layers at around 5-km elevation in the tropics. There are two candidate processes that are able to explain the occurrence of cloudy layers in the middle level: cloud detrainment promoted by the stable layer and enhanced condensation to compensate for melting cooling. In the present study, the authors used a cloud-resolving nonhydrostatic model and conducted numerical simulations of a squall line to clarify the process responsible for the formation of midlevel thin cloud, especially the cloud at the 0°C level. In a two-dimensional control experiment thin cloud was simulated in the middle level, and cloud coverage showed a notable peak just below the 0°C level for environments without a stable layer in the initial temperature profile. Enhanced and weakened stability layers simultaneously appeared above and below the peak level of the cloud coverage. The formation of midlevel thin cloud is associated with intensified condensation to compensate for strong cooling due to the melting of ice particles. The enhancement of condensation continues until ice is no longer provided to the cloud at the melting level. This means that the cloud survives for a longer period than cloud at other levels. To investigate the influence of the commonly observed tropical stable layer on the occurrence of midlevel thin cloud, the authors performed three sensitivity tests in which a warm rain microphysics scheme was employed and/or the initial temperature profile had enhanced and weakened stability layers in the middle level. Comparisons among the control and sensitivity experiments revealed that intensified condensation related to melting cooling plays a critical role in the formation of midlevel thin cloud, although the stable layer is associated with the inhibition of convection growth in the middle level. A three-dimensional experiment under more realistic conditions simulated cloud formation at the 0°C level, although the peak of the cloud coverage was less prominent than those in the two-dimensional experiments.

scholarly journals Laser-produced blast wave and numerical simulation using the FLASH code

2005 ◽  
Vol 23 (4) ◽  
pp. 513-519 ◽  
Author(s):  
D.R. FARLEY ◽  
K. SHIGEMORI ◽  
H. AZECHI
Keyword(s):  
Numerical Simulation ◽  
Temperature Profile ◽  
Blast Wave ◽  
Thermal Wave ◽  
Initial Temperature ◽  
Radiative Cooling ◽  
Gas Evolution ◽  
Two Dimensional ◽  
Nitrogen Gas ◽  
Spot Radius

Two-dimensional (2D) FLASH simulations were run with Spitzer-Härm conductivity on and off in an attempt to simulate a laser-produced blast wave. Dissociation, ionization, recombination, and radiative cooling were not included. An initial Gaussian temperature profile with T0 = 120 eV and spot radius r0 = 25 μm was used assuming 1 μm thickness of the CH disk is ablated into the background nitrogen gas. Evolution of the blast wave differs slightly between the cases of Spitzer-Härm on and off, and neither case matches well with experiment. Due to the high temperatures involved, a thermal wave should be expected such that the Spitzer-Härm conductivity on case is more likely. A simulation run with an initial temperature of ∼ 4 keV might match better with experiment.

scholarly journals Towards explicit regulating-ion-transport: nanochannels with only function-elements at outer-surface

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Qun Ma ◽  
Yu Li ◽  
Rongsheng Wang ◽  
Hongquan Xu ◽  
Qiujiao Du ◽  
...  
Keyword(s):  
Ion Transport ◽  
Numerical Simulations ◽  
Power Density ◽  
Outer Surface ◽  
Internal Resistance ◽  
Porous Membranes ◽  
Two Dimensional ◽  
Ionic Selectivity ◽  
Key Features ◽  
Energy Conversion Devices

AbstractFunction elements (FE) are vital components of nanochannel-systems for artificially regulating ion transport. Conventionally, the FE at inner wall (FEIW) of nanochannel−systems are of concern owing to their recognized effect on the compression of ionic passageways. However, their properties are inexplicit or generally presumed from the properties of the FE at outer surface (FEOS), which will bring potential errors. Here, we show that the FEOS independently regulate ion transport in a nanochannel−system without FEIW. The numerical simulations, assigned the measured parameters of FEOS to the Poisson and Nernst-Planck (PNP) equations, are well fitted with the experiments, indicating the generally explicit regulating-ion-transport accomplished by FEOS without FEIW. Meanwhile, the FEOS fulfill the key features of the pervious nanochannel systems on regulating-ion-transport in osmotic energy conversion devices and biosensors, and show advantages to (1) promote power density through concentrating FE at outer surface, bringing increase of ionic selectivity but no obvious change in internal resistance; (2) accommodate probes or targets with size beyond the diameter of nanochannels. Nanochannel-systems with only FEOS of explicit properties provide a quantitative platform for studying substrate transport phenomena through nanoconfined space, including nanopores, nanochannels, nanopipettes, porous membranes and two-dimensional channels.

Two-dimensional metal carbides and nitrides (MXenes): preparation, property, and applications in cancer therapy

Nanophotonics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 2125-2145 ◽  
Author(s):  
Lu Ming Dong ◽  
Cui Ye ◽  
Lin Lin Zheng ◽  
Zhong Feng Gao ◽  
Fan Xia
Keyword(s):  
Cancer Therapy ◽  
Scientific Community ◽  
Critical Role ◽  
High Specific Surface Area ◽  
Future Perspective ◽  
Two Dimensional ◽  
Metal Carbides ◽  
Practical Applications ◽  
Two Dimensional Materials ◽  
Size And Morphology

AbstractTransition metal carbides and nitrides (MXenes), which comprise a rapidly growing family of two-dimensional materials, have attracted extensive attention of the scientific community, owing to its unique characteristics of high specific surface area, remarkable biocompatibility, and versatile applications. Exploring different methods to tune the size and morphology of MXenes plays a critical role in their practical applications. In recent years, MXenes have been demonstrated as promising nanomaterials for cancer therapy with substantial performances, which not only are helpful to clarify the mechanism between properties and morphologies but also bridge the gap between MXene nanotechnology and forward-looking applications. In this review, recent progress on the preparation and properties of MXenes are summarized. Further applications in cancer therapy are also discussed. Finally, the current opportunities and future perspective of MXenes are described.

The Best Perturbation Method for the Parameter Inversion of Two-Dimension Convection-Diffusion Equation

2013 ◽  
Vol 380-384 ◽  
pp. 1143-1146
Author(s):  
Xiang Guo Liu
Keyword(s):  
Inverse Problem ◽  
Diffusion Equation ◽  
Perturbation Method ◽  
Numerical Simulations ◽  
Numerical Solution ◽  
Two Dimensional ◽  
Convection Diffusion ◽  
Convection Diffusion Equation ◽  
Parameter Inversion ◽  
Parametric Inversion

The paper researches the parametric inversion of the two-dimensional convection-diffusion equation by means of best perturbation method, draw a Numerical Solution for such inverse problem. It is shown by numerical simulations that the method is feasible and effective.

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