COMPUTER SIMULATION OF PARTICLE VELOCITY IN A CYCLONE

The article sets the goal of determining and calculating the speed of accelerated movement of particles in the gas-dust flow of an air cyclone, depending on the size of the cyclone, the physical properties of the particle and the gas-dust flow. A method for constructing a computer model of the motion of a particle in a roaring gas-dust flow of a cyclone is presented. The sequence of formalization of the computer model of the process of sedimentation of particles of a gas-dust flow of a cyclone unit is based on the theoretical foundations of aerodynamics and touches on the most significant aspects of the development of a cyclone. Attention paid to the analysis of the dynamics of particle motion in a centrifugal field, accelerated motion and a realistic estimate of the particle velocity. The mutual influences of five forces are considered. This is the centrifugal force, the force of resistance of the gas-dust flow, the forces of gravity, the Archimedean force and the force of inertia, acting on the accelerating motion of the particle in the flow. On the basis of the block principle, a general computer model of the cycloning process is built, which makes it possible to calculate the uneven velocity of a particle in a gas-dust flow. Analytical methods for evaluating the acceleration parameters and the main methods of numerical analysis of the dynamics of particle motion, shows that the main advantage of up to 0.8 seconds is the accelerated motion of a particle in a gas-dust flow under the given conditions. During this time, most of the particles reach the cyclone wall. This shows that the determination of the accelerating motion of a particle plays an important role in cyclones.

VACUUM BASED WIPING SYSTEM FOR POLLEN AND DUST FREE SURFACES - IN A CASE STUDY WITH BLACKBOARD

Due to the sharp growth in technologies, humans demand high-performance machines to perform their tasks to make their life a bit effortless. This wiping system is made to ease the monotonous job of erasing blackboards by teachers. In this paper, a roller wiper is used that is rested upon the blackboard and it moves in line with the split-up made in blackboard using a DC motor and collects the dust spontaneously using a vacuum cleaner. To push and pull the roller wiper a servomotor is accustomed, and the position of the wiper is automated by an Arduino. Thus, it eludes the dust flow to the atmosphere thereby averting health issues triggered by dust and keeping the environment clean.

Inner dusty regions of protoplanetary discs – II. Dust dynamics driven by radiation pressure and disc winds

ABSTRACT We explore dust flow in the hottest parts of protoplanetary discs using the forces of gravity, gas drag, and radiation pressure. Our main focus is on the optically thin regions of dusty disc, where the dust is exposed to the most extreme heating conditions and dynamical perturbations: the surface of optically thick disc and the inner dust sublimation zone. We utilize results from two numerically strenuous fields of research. The first is the quasi-stationary solutions on gas velocity and density distributions from mangetohydrodynamical (MHD) simulations of accretion discs. This is critical for implementing a more realistic gas drag impact on dust movements. The second is the optical depth structure from a high-resolution dust radiation transfer. This step is critical for a better understanding of dust distribution within the disc. We describe a numerical method that incorporates these solutions into the dust dynamics equations. We use this to integrate dust trajectories under different disc wind models and show how grains end up trapped in flows that range from simple accretion on to the star to outflows into outer disc regions. We demonstrate how the radiation pressure force plays one of the key roles in this process and cannot be ignored. It erodes the dusty disc surface, reduces its height, resists dust accretion on to the star, and helps the disc wind in pushing grains outwards. The changes in grain size and porosity significantly affect the results, with smaller and porous grains being influenced more strongly by the disc wind and radiation pressure.

The origin of tail-like structures around protoplanetary disks

Aims. We study the origin of tail-like structures recently detected around the disk of SU Aurigae and several FU Orionis-type stars. Methods. Dynamic protostellar disks featuring ejections of gaseous clumps and quiescent protoplanetary disks experiencing a close encounter with an intruder star were modeled using the numerical hydrodynamics code FEOSAD. Both the gas and dust dynamics were taken into account, including dust growth and mutual friction between the gas and dust components. Only plane-of-the-disk encounters were considered. Results. Ejected clumps produce a unique type of tail that is characterized by a bow-shock shape. Such tails originate from the supersonic motion of ejected clumps through the dense envelope that often surrounds young gravitationally unstable protostellar disks. The ejected clumps either sit at the head of the tail-like structure or disperse if their mass is insufficient to withstand the head wind of the envelope. On the other hand, close encounters with quiescent protoplanetary disks produce three types of the tail-like structure; we define these as pre-collisional, post-collisional, and spiral tails. These tails can in principle be distinguished from one another by particular features of the gas and dust flow in and around them. We find that the brown-dwarf-mass intruders do not capture circumintruder disks during the encounter, while the subsolar-mass intruders can acquire appreciable circumintruder disks with elevated dust-to-gas ratios, which can ease their observational detection. However, this is true only for prograde collisions; the retrograde intruders fail to collect appreciable amounts of gas or dust from the disk of the target. The mass of gas in the tail varies in the range 0.85–11.8 MJup, while the total mass of dust lies in the 1.75–30.1 M⊕ range, with the spiral tails featuring the highest masses. The predicted mass of dust in the model tail-like structures is therefore higher than what was inferred for similar structures in SU Aur, FU Ori, and Z CMa, making their observational detection feasible. Conclusions. Tail-like structures around protostellar and protoplanetary disks can be used to infer interesting phenomena such as clump ejection or close encounters. In particular, the bow-shock morphology of the tails could point to clump ejections as a possible formation mechanism. Further numerical and observational studies are needed to better understand the detectability and properties of the tails.

Numerical study of the dust-air current around the spherical suction unit screened by the circular swirling jet. Part 1. Air-jet currents

The hazardous substances screening by means of the local suction ventilation which element is the local suction gun is regarded in the article. The influence was investigated of the size ratio between the suction gun and he ring opening dimensions, as well as of the drawn in-incoming air ratio on both of the suction gun's air gripping distance and on the dust flow reducing in the local closed type suction guns. The local suction guns were regarded in the unrestricted, half-restricted and restricted spaces.Ill.3. Ref. 20.