The potential for sea ice-albedo feedback to give rise to nonlinear climate change in the Arctic Ocean – defined as a nonlinear relationship between polar and global temperature change or, equivalently, a time-varying polar amplification – is explored in IPCC AR4 climate models. Five models supplying SRES A1B ensembles for the 21 st century are examined and very linear relationships are found between polar and global temperatures (indicating linear Arctic Ocean climate change), and between polar temperature and albedo (the potential source of nonlinearity). Two of the climate models have Arctic Ocean simulations that become annually sea ice-free under the stronger CO 2 increase to quadrupling forcing. Both of these runs show increases in polar amplification at polar temperatures above-5 o C and one exhibits heat budget changes that are consistent with the small ice cap instability of simple energy balance models. Both models show linear warming up to a polar temperature of-5 o C, well above the disappearance of their September ice covers at about-9 o C. Below-5 o C, surface albedo decreases smoothly as reductions move, progressively, to earlier parts of the sunlit period. Atmospheric heat transport exerts a strong cooling effect during the transition to annually ice-free conditions. Specialized experiments with atmosphere and coupled models show that the main damping mechanism for sea ice region surface temperature is reduced upward heat flux through the adjacent ice-free oceans resulting in reduced atmospheric heat transport into the region.

Geophysical fluid dynamics.

Solidification microstructures and solid-state parallels: Recent developments, future directions

Although the Hertz-Knudsen (HK) relation is often used to correlate evaporation data, the relation contains two empirical parameters (the evaporation and condensation coefficients) that have inexplicably been found to span 3 orders of magnitude. Explicit expressions for these coefficients have yet to be determined. This review will examine sources of error in the HK relation that have led to the coefficients’ scatter. Through an examination of theoretical, experimental, and molecular dynamics simulation studies of evaporation, this review will show that the HK relation is incomplete, since it is missing an important physical concept: the coupling between the vapor and liquid phases during evaporation. The review also examines a modified HK relation, obtained from the quantum-mechanically based statistical rate theory (SRT) expression for the evaporation flux and applying a limit to it in which the thermal energy is dominant. Explicit expressions for the evaporation and condensation coefficients are define...

Expressions for the Evaporation and Condensation Coefficients in the Hertz-Knudsen Relation.

Inkjet printing is recognised as an efficient method for direct deposition of functional materials on flexible substrates in predesigned patterns owing to simple processing, low cost and higher adaptability for large scale fabrication of electronic devices, sensors, light emitting diodes, etc. Inks used in inkjet printing mostly consist of organic polymers, metal nanoparticles and carbon materials such as graphene and carbon nanotubes. For effectiveness of the printing process, the fluid dynamic parameters such as viscosity and surface tension, as well as dimensionless quantities such as the Weber number, Reynolds number, and Ohnesorge number, must be within a suitable limit. More frequently, this process suffers due to the formation of a coffee ring during the post printing process, which affects the morphology as well as electrical conductivity of the printed pattern. In this review, we have summarized the various aspects of inks such as fluid dynamical parameters of inks, mechanism of the coffee ring formation, different types of ink preparation strategies and their applications in sensors, thin film transistors, and energy storage devices.

A review on inkjet printing of nanoparticle inks for flexible electronics

The wetting of solid surfaces using liquid droplets has been studied since the early 1800s. Thomas Young and Pierre-Simon Laplace investigated the wetting properties, as well as the role of the contact angle and the coupling of a liquid and solid, on the contact angle formation. The geometry of a sessile droplet is relatively simple. However, it is sufficiently complex to be applied for solving and prediction of real-life situations (for example, metallic inks for inkjet printing, the spreading of pesticides on leaves, the dropping of whole blood, the spreading of blood serum, and drying for medical applications). Moreover, when taking into account both wetting and evaporation, a simple droplet becomes a very complex problem, and has been investigated by a number of researchers worldwide. The complexity is mainly due to the physics involved, the full coupling with the substrate upon which the drop is deposited, the atmosphere surrounding the droplet, and the nature of the fluid (pure fluid, bi- or multi-phase mixtures, or even fluids containing colloids and/or nano-particles). This review presents the physics involved during droplet wetting and evaporation by focusing on the evaporation dynamics, the flow motion, the vapour behaviour, the surface tension, and the wetting properties.

Recent advances in droplet wetting and evaporation

SJ-10 program provides a mission of space microgravity experiments including both fields of microgravity science and space life science aboard the 24th recoverable satellite of China. Scientific purpose of the program is to promote the scientific research in the space microgravity environment by operating the satellite at lower earth orbit for 2 weeks. There are totally 27 experiments, including 17 ones in the field of microgravity science (microgravity fluid physics 6, microgravity combustion 3, and space materials science 8) and 10 in the field of space life science (radiation biology 3, gravitational biology 3, and space biotechnology 4). These experiments were selected from more than 200 applications. The satellite will be launched in the end of 2015 or a bit later. It is expected that many fruitful scientific results on microgravity science and space life science will be contributed by this program.

http://sm08.iphy.ac.cn/resource/Paper/2014/hou4.pdf

Space Program SJ-10 of Microgravity Research

Thermal effects of substrate on Marangoni flow in droplet evaporation: Response surface and sensitivity analysis

The problem of a film flowing down an inclined porous layer is considered The fully developed basic flow is driven by gravitation A careful linear instability analysis is carried out We use Darcy's law to describe the porous layer and solve the coupling equations of the fluid and the porous medium rather than the decoupled equations of the one-sided model used in previous works The eigenvalue problem is solved by means of a Chebyshev collocation method We compare the instability of the two-sided model with the results of the one-sided model The result reveals a porous mode instability which is completely neglected in previous works For a falling film on an inclined porous plane there are three instability modes, ie, the surface mode, the shear mode, and the porous mode We also study the influences of the depth ratio d, the Darcy number delta, and the Beavers-Joseph coefficient alpha(BJ) on the instability of the system

/pdf/instabilities-of-a-liquid-film-flowing-down-an-inclined-2uuzszsht1.pdf

Instabilities of a liquid film flowing down an inclined porous plane

The instability of Poiseuille flow in a fluid-porous system is investigated. The system consists of a fluid layer overlying porous media and is subjected to a horizontal plane Poiseuille flow. We use Brinkman's model instead of Darcy's law to describe the porous layer. The eigenvalue problem is solved by means of a Chebyshev collocation method. We study the influence of the depth ratio (d) over cap and the Darcy number delta on the instability of the system. We compare systematically the instability of Brinkman's model with the results of Darcy's model. Our results show that no satisfactory agreement between Brinkman's model and Darcy's model is obtained for the instability of a fluid-porous system. We also examine the instability of Darcy's model. A particular comparison with early work is made. We find that a multivalued region may present in the (k, Re) plane, which was neglected in previous work. Here k is the dimensionless wavenumber and Re is the Reynolds number. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3000643]

Instability of plane Poiseuille flow in a fluid-porous system

We present in this paper results obtained from a parabolic flight campaign regarding ethanol sessile drop evaporation under reduced gravity conditions. Drops are created using a syringe pump by means of injection through a PTFE (polytetrafluoroethylene) substrate. The drops are recorded using a video camera and an infrared camera to observe the thermal motion inside the drop and on the heating substrate. The experimental set-up presented in this paper enables the simultaneous visualization and access to the heat flux density that is transferred to the drop using a heat flux meter placed between the heating block and the PTFE substrate. We evidence original thermal spreading phenomena during the ethanol drop creation on a heated PTFE substrate. The drop exhibits specific behaviour which is discussed here. This work is performed in the frame of a French-Chinese collaboration (project IMPACHT) for future experiments in a Chinese scientific satellite.

Qiu-Sheng Liu

Papers

Space Program SJ-10 of Microgravity Research

Thermal effects of substrate on Marangoni flow in droplet evaporation: Response surface and sensitivity analysis

Instabilities of a liquid film flowing down an inclined porous plane

Instability of plane Poiseuille flow in a fluid-porous system

Evaporation of Ethanol Drops on a Heated Substrate Under Microgravity Conditions