Numerical Modelling of Erythrocyte Sticking Mechanics

The mechanics of thrombus formation includes the interaction of platelets, fibrin, and erythrocytes. The interaction was analyzed as the erythrocyte approaches the activated platelet and fibrin thrombus formation. The discrete element method (DEM) was used for the numerical experiment. Details of numerical experiments are presented by analyzing the dynamics of an erythrocyte in the process of interaction; a history of force, velocity, and displacement is given. It is usually assumed that the objects modeled by the DEM can oscillate during the sticking process. Modeling only this requires specialized knowledge and long-term research. However, by taking into account the influence of the fluid and modeling a soft biological cell, a completely different behavior can be achieved using the DEM method. The results of the numerical experiment show the different behavior of the erythrocyte when it interacts with a certain surface. Without taking into account the influence of the fluid in the sticking process, oscillations of the erythrocyte are observed. Meanwhile, after evaluating the influence of the liquid on the sticking process, there are no oscillations and unloading processes, which are typical for ultrafine objects. It is hoped that this will contribute to the study of the complex process of thrombus formation

Numerical Modeling of Thrombocyte Interaction Mechanics with a Blood Vessel Wall

A platelet (thrombocyte) can be in two states, activated and inactivated. The paper analyzes the interaction of an inactive platelet cell with the wall of a blood vessel. The goal is to analyze and represent the dynamics of platelet cell interaction when a thrombus has not yet formed. The discrete element method (DEM) can be used for the presented model. The paper presents an analysis of the dependence of force and displacement. This test is an introduction to more advanced tests when a blood clot forms

Air Pollution with Fine Particles in Closed Parking and Theoretical Studies of the Interaction of Inhaled Particles in Respiratory Tract

Indoor air quality must be considered important in regards to its possible harmful effects on the human body. Premises such as underground garages, covered car parks and other similar structures remain crucial in assessing the level of air pollution. In such an environment, the main sources of pollution are motor vehicles, emissions from the heating-ventilation-air-conditioning systems of the engineering networks of the joint building, and pollution. When visiting such premises, a person inhales the air, which contains fine particulate matter and a variety of gaseous pollutants harmful to health. The aim of this study is to assess indoor air pollution with fine particulate matter of 0.3–10 µm depending on the nature of the source, aerodynamic parameters in relation to the potential location of a person, and the mechanical behavior of inhaled particles with respiratory tissues. In this work, the interaction of a fine particle with an alveolar cell is theoretically studied when the particle enters the lungs through the human respiratory tract. Based on the results of this study, it would be possible to assess the extent of pollution and the movement or accumulation of particles in the respiratory system

Modelling deformable boundary by spherical particle for normal contact

The normal contact of the elastic spherical particle with deformable boundary is investigated in terms of the Discrete Element Method (DEM). The particle of the prescribed radius is moving under gravity and the initial velocity. The deformable boundary is treated as rigidly fixed spherical particle with variable elasticity modulus and variable radius. The limit case, approaching the infinite radius presents an elastic half-space, while increasing of the elasticity modulus presents the rigid boundary, respectively. The linear model and the nonlinear Hertz contact model used in the discrete element method are investigated numerically by applying the 5th-order Gear’s predictorcorrector integration scheme. The numerical model is tested by comparing it with analytical solution. The time variations of the particle positions, velocities and accelerations are presented. On the basis of simulation results the limit values of the boundary particle parameters are evaluated and recommendations for the boundary particle parameters required in DEM simulation are drown

Objective Function Distortion Reduction in Identification Technique of Composite Material Elastic Properties

In studies of structural mechanics, modal analysis, presented in this paper, is an important tool for analyzing the vibration of an object and its frequencies. In modal analysis, different modes of vibration and the frequencies that generate them are considered. The study covers the nondestructive identification of the elastic characteristics of materials, which involves stochastic algorithms and the application of reverse engineering (i.e., the comparison of reference eigenfrequencies with the results of mathematical models). Identification is achieved by minimizing the objective function—the smaller the value of the objective function, the higher the identification accuracy obtained. By changing the parameters of a material’s mathematical model during identification, certain (usually higher order) modes can change places in a natural frequency spectrum. This leads to the comparison of different order eigenfrequencies, slow convergence and poor accuracy of the identification process. The technique involved in this work is the mode-shape recognition of a specimen of material with an “incorrect” set of elastic properties. The results prove that the identification accuracy of a material’s elastic properties can be increased if an “incorrect” set of elastic properties is removed from the identification process. The research covers only numerical research, with a physical experiment simulation

Air Pollution with Fine Particles in Closed Parking and Theoretical Studies of the Interaction of Inhaled Particles in Respiratory Tract

Indoor air quality must be considered important in regards to its possible harmful effects on the human body. Premises such as underground garages, covered car parks and other similar structures remain crucial in assessing the level of air pollution. In such an environment, the main sources of pollution are motor vehicles, emissions from the heating-ventilation-air-conditioning systems of the engineering networks of the joint building, and pollution. When visiting such premises, a person inhales the air, which contains fine particulate matter and a variety of gaseous pollutants harmful to health. The aim of this study is to assess indoor air pollution with fine particulate matter of 0.3–10 µm depending on the nature of the source, aerodynamic parameters in relation to the potential location of a person, and the mechanical behavior of inhaled particles with respiratory tissues. In this work, the interaction of a fine particle with an alveolar cell is theoretically studied when the particle enters the lungs through the human respiratory tract. Based on the results of this study, it would be possible to assess the extent of pollution and the movement or accumulation of particles in the respiratory system

Investigation of Color Reproduction on Linen Fabrics when Printing with Mimaki TX400-1800D Inkjet with Pigment TP250 Dyes

The aim of this research is to investigate related effect of dyeability to linen textiles related to different printing parameters. The study investigated the change in color characteristics when printing on linen fabrics with an inkjet MIMAKI Tx400-1800D printer with pigmented TP 250 inks. The dependence of color reproduction on linen fabrics on the number of print head passes, number of ink layers to be coated, linen fabric density, and different types of linen fabric was investigated. All this affects the quality of print and its mechanical properties. The change in color characteristics on different types of linen fabrics was determined experimentally. We determine at which print settings the most accurate color reproduction can be achieved on different linen fabrics. The difference between the highest and the lowest possible number of head passages was investigated. The possibilities of reproducing different linen fabric colors were determined

Numerical Study of the Flow of Pollutants during Air Purification, Taking into Account the Use of Eco-Friendly Material for the Filter—Mycelium

To improve air quality, it is customary to apply technological measures to isolate or retain pollutants by influencing the polluted stream in various ways to effectively remove the pollutants. One of the most commonly used measures is a filter, in which the air flow passes through a porous aggregate. A variety of filter materials allows very selective and precise cleaning of the air flow in non-standard or even aggressive microclimate conditions. In this paper, the environmental aspect of the used materials is discussed, and a theoretical model of an adapted mycelium is proposed as an alternative to the use of filter materials to predict air flow purification. In the created numerical model of an idealized filter, several cases are considered when the pore size of the mycelial fillers reaches 1.0, 0.5 and 0.1 mm, and the feed flow velocity reaches 1–5 m/s. Moreover, in the mycelium itself, the flow velocity can decrease and approach the wall to a value of 0.3 m/s, which is estimated for additional numerical studies of interaction with the surface. These preliminary studies are aimed at establishing indicative theoretical parameters for favorable air flow movement in the structure of the mycelium

The Optimization of the Geometry of the Centrifugal Fan at Different Design Points

The optimization of the geometry of a centrifugal fan is performed at maximum power and high-efficiency design points (DPs) to improve impeller efficiency. Two design variables defining the shape of fan blade are selected for the optimization. The optimal values of the geometry parameters of the impeller blades are identified by employing virtual flow simulations. The results of virtual experiments indicate the influence of the parameters of the blade geometry on its efficiency. With the optimization of impeller blade geometry, the efficiency of the fan is improved with respect to the reference model, as confirmed by comparing the performance curves. Herein, we discuss the results obtained in virtual tests by identifying the influence of DPs on the performance characteristics of centrifugal fans

Simulation of sticking of adhesive particles under normal impact

Sticking of adhesive spherical particles under normal impact is investigated numerically by applying the Discrete Element Method. The nonlinear-dissipative contact model with adhesion is applied to model normal contact forces. Loading is described by elastic Hertz and elastic-plastic contact model with history-dependent adhesion. Damping is described by nonlinear Tsuji model. Adhesion limit is of linear character while particle detachment is of non-linear nature. Sticking and detachment behaviour for various damping values are considered in detail. Influence of the adhesion force for a wide range of particle sizes is illustrated by the variation of critical sticking velocity. Comparison of purely elastic with elastic-plastic behaviour is also presented