Tricolor Technique for Visualization of Spatial Variations of Polydisperse Dust in Gas-Dust Flows

Abstract

The aim of this work is to construct an algorithm for visualizing a polydisperse phase of solid particles (dust) in an inhomogeneous flow of a two-phase gas-dust mixture that would allow us to see, within one plot, the degree of polydispersity of the dust phase and the difference in the spatial distributions of individual fractions of dust particles in the computational domain. The developed technique allows us to reproduce concentrations from one to three fractions of dust particles in each cell in the computational domain. Each of the three fractions of dust particles is mapped to one of the main channels of the RGB palette.The intensity of the color shade is set to be proportional to the relative concentration of dust particles in this fraction. The final image for a polydisperse mixture is obtained by adding images in each of the three color channels. To visualize the degree of polydispersity, I propose depicting the spatial distribution of the entropy of the dust mixture. The definition of the entropy of a mixture is generalized to take into account the states of a mixture with zero number of particles in the mixture. They correspond to dust-free sections of the computational domain (voids). The proposed method for visualizing the polydispersity of a mixture of particles is demonstrated using the example of dynamic numerical modeling of the spatial features of dust structures formed in turbulent gas-dust flows and in flows with shock waves.Real liquid, gas or plasma media have an inhomogeneous structure and are complex, composite systems that include microobjects of different types and different nature, such as small solid suspended particles, droplets or bubbles. There are a huge number of areas in the field of technology in which a person deals with multiphase environments, from chemical reactors to engine building and aeronautics. There are no manifestations of polyphase in nature that are less significant. Despite the small relative mass content, impurity aerosol or dust particles can play an important role in the life of planetary atmospheres, interstellar or intergalactic gas. The dust component determines the optical properties of the medium, its opacity in one interval or another of the electromagnetic spectrum. As a consequence, dust in the atmosphere or in the interstellar gas can act as a coolant, realizing the anti-greenhouse effect [1,2]. Due to their windage, dust grains can cause an effective mechanical effect of star radiation on a transparent neutral gas, accelerating under the influence of radiation pressure and accelerating the surrounding matter [3,4]. Particles of dust in the interstellar gas act as a catalyst for the process of gas molecularization [1]. Dust also serves as a building material for the formation of solid celestial bodies, such as asteroids or planets [1].Examples of space objects enriched with impure dust particles are gas-dust interstellar clouds and nebulae, protoplanetary disks, spiral arms of galaxies and gas-dust halos of galaxies. Usually, cosmic dust grains are par...

Image Registration with Particles, Examplified with the Complex Plasma Laboratory PK-4 on Board the International Space Station

“…This is a first indication that Method II might be superior in this case, but it provides no quantitative measure. For this purpose, we made color movies of the region around the overlap region encoded in the RGB scheme, inspired by Korolev et al [39]. These movies show the images of Camera 1 in the red channel and the transformed images of Camera 2 in the blue channel (see Figure 8).…”

Visualization of the Anisotropy of the Velocity Dispersion and Characteristics of the Multi-Velocity Continuum in the Regions of Multi-Stream Flows of Gas-Dust Media with Polydisperse Dust

“…We developed visualization tools using the example of a two-dimensional dynamic model of a turbulent interstellar gas-dust matter passing through the spiral arm of a disk galaxy. Details of modeling, basic equations, and a justification of the applicability of certain approximations can be found in our work [ 22 ]. Unlike the model presented in [ 22 ], here, we are considering not a horizontal, but a vertical section of the spiral arm and its galactic surroundings.…”

“…Details of modeling, basic equations, and a justification of the applicability of certain approximations can be found in our work [ 22 ]. Unlike the model presented in [ 22 ], here, we are considering not a horizontal, but a vertical section of the spiral arm and its galactic surroundings. Here, we will only briefly list the main features of the model.…”

“…We consider two-dimensional distributions ( ). To visualize the distributions of the anisotropies of the velocity dispersions for several fractions simultaneously in one figure, we propose, in the spirit of our work [ 22 ], to represent these distributions using a certain indicator (function of object features) characterizing the degree of diversity of the distribution of features in the sample. Shannon’s entropy is often taken as a measure of diversity.…”

“…The visualization of multi-field distributions has limited resources. As there are only three basic colors in all colorimetric systems, up to three scalar fields can be visualized simultaneously in one drawing, restoring their values as coefficients of decomposition of an arbitrary color into three basic components [ 22 , 23 ]. On the other hand, for visualization, geometrical objects (glyphs) of any complex structure can be used, and these can be information-intensive, but difficult to perceive.…”