Delta distribution of electronegative plasma predicted by reformed“spring oscillator”dynamic equation with dispersing force

In our relevant paper[Zhao S X(2021)Chin.Phys.B 30055201],a delta distribution of negative ions is given by fluid simulation and preliminarily explained by decomposed anions transport equation.In the present work,first,the intrinsic connection between the electropositive plasma transport equation and spring oscillator dynamic equation is established.Inspired by this similarity,reformed“spring oscillator”equation with dispersing instead of restoring force that gives quasi-delta solution is devised according to the math embodied in the anion equation,which is of potential significance to the disciplines of atomic physics and astronomy as well.For solving the“diffusion confusion”the physics that determines the delta profile within the continuity equation is explored on the basis that recombination loss source term plays the role of drift flux,which is applicable for fluid model of low temperature plasma,but not the ordinary fluid dynamics.Besides,the math and physics revealed in this work predict that the ratio of recombination or attachment(for electrons)frequency versus the species diffusion coefficient is a very important parameter in determining the delta distribution,as it acts as the acceleration of object,according to the reformed oscillator equation.With this theory,the analogous delta profile of electrons density in the famous drift and ambi-polar diffusion heating mechanism of electronegative capacitively coupled plasma is interpreted.

Influence of Rare Earth Composite Phosphate on Surface Free Energy of Ceramic Glaze

Rare earth composite phosphate (RECP) was doped into the ceramic glazes. The contact angle and surface free energy were characterized by the OCA-30 automatism contact angle test system. Through studied the influence of RECP on the surface free energy of ceramic glaze and movement modality of oil on the ceramic glaze in the water, the results show that the ceramic surface free energy increase obviously after dope RECP. Analysis and calculation show that the surface free energy increase mainly profited from the surface hydroxyl groups increase.

Viscoelastic modeling of the diffusion of polymeric pollutants injected into a pipe flow

This study focuses on the transient analysis of nonlinear dispersion of a polymeric pollutant ejected by an external source into a laminar pipe flow of a Newtonian liquid under axi-symmetric conditions.The influence of density variation with pollutant concentration is approximated according to the Boussinesq approximation and the nonlinear governing equations of momentum,pollutant concentration are obtained together with and Oldroyd-B constitutive model for the polymer stress.The problem is solved numerically using a semi-implicit finite difference method.Solutions are presented in graphical form for various parameter values and given in terms of fluid velocity,pollutant concentration,polymer stress components,skin friction and wall mass transfer rate.The model can be a useful tool in understanding the dynamics of industrial pollution situations arising from improper discharge of hydrocarbon pollutants into,say,water bodies.The model can also be quite useful for available necessary early warning methods for detecting or predicting the scale of pollution and hence help mitigate related damage downstream by earlier instituting relevant decontamination measures.

NUMERICAL CALCULATION OF LONDON-VAN DER WAALS ADHESION FORCE DISTRIBUTIONS FOR DIFFERENT SHAPED PARTICLES

A basic method to calculate van der Waals dispersion force distributions for submicron superquadric particles in particle-wall systems is presented. The force distribution is achieved by rotating particles through a large number of arbitrary spatial orientations, each time keeping constant the contact distance to the wall surface while calculating the dispersion force. To accomplish this, the use of 2D particle shape suffices, that is, through using an inter-dimensional function, which has been determined previously. A further development of the method within digital image analysis may lead to possible applications to forecasting the macroscopic properties of particle systems, for example, flowability, agglomeration behavior or dispersibility. For small ranges of superquadric particle shapes, each with a different size, the way from determining the inter-dimensional function up to applying image analysis is shown in an example.

Particles dispersion on fluid-liquid interfaces

This paper is concerned with the dispersion of particles on the fluid-liquid interface. In a previous study we have shown that when small particles, e.g., flour, pollen, glass beads, etc., contact an air-liquid interface, they disperse rapidly as if they were in an explosion. The rapid dispersion is due to the fact that the capillary force pulls particles into the interface causing them to accelerate to a large velocity. In this paper we show that motion of particles normal to the interface is inertia dominated; they oscillate vertically about their equilibrium position before coming to rest under viscous drag. This vertical motion of a particle causes a radially-outward lateral （secondary） flow on the interface that causes nearby particles to move away. The dispersion on a liquid-liquid interface, which is the primary focus of this study, was relatively weaker than on an air-liquid interface, and occurred over a longer period of time. When falling through an upper liquid the particles have a slower velocity than when falling through air because the liquid has a greater viscosity. Another difference for the liquid-liquid interface is that the separation of particles begins in the upper liquid before the particles reach the interface. The rate of dispersion depended on the size of the particles, the densities of the particle and liquids, the viscosities of the liquids involved, and the contact angle. For small particles, partial pinning and hysteresis of the three-phase contact line on the surface of the particle during adsorption on liquid-liquid interfaces was also important. The frequency of oscillation of particles about their floating equilibrium increased with decreasing particle size on both air-water and liquid-liquid interfaces, and the time to reach equilibrium decreased with decreasing particle size. These results are in agreement with our analysis.

A novel bird-nest-like air superoleophobic/superhydrophilic Cu(OH)2-based composite coating for efficient oil–water separation

An air superoleophobic/superhydrophilic composite coating with a unique structure was fabricated by oxidation and further modification of the copper mesh,and its design principle was clarified.This unique bird-nest-like configuration gives it instant superhydrophilicity due to the high surface roughness and high polar surface free energy components,while air superoleophobicity is caused by its extremely low dispersive surface free energy components.Furthermore,a water-resistance mechanism was proposed whereby a polyelectrolyte plays a critical role in improving the water-resistance of fluorosurfactants.It can separate oil–water mixtures with high efficiency(98.72%)and high flux(25185 L·m−2·h−1),and can be reused.In addition,our composite coating had certain anti-acid,anti-alkali,anti-salt and anti-sand impact performance.More importantly,after being soaked in water for a long time or being exposed to the air for a long time,it still retained ultra-high air oil contact angle and showed excellent stability,which provided the possibility for practical applications.Thus,these findings offer the potential for significant practical applications in managing oily wastewater and marine oil spill incidents.