Marian Bojko

CFD modelling for atmospheric pollutants/aerosols studies within the complex terrains of urban areas and industrial sites

Computational fluid dynamic (CFD) modelling of pollution dispersion and chemical conversion to aerosol particles in the atmospheric boundary layer (ABL) has been studied. The investigation focused on the numerical modelling above complex orographic terrains of urban areas and industrial sites including the dispersion of toxic substances in the air as a result of accidents. A finite-rate model of chemical reactions, including the turbulence chemistry for modelling the reaction between nitric acid and ammonia, has been applied. As supporting experiments, online monitoring of the spatial distribution of pollutants and aerosols has been performed above real complex areas. Minimal detectable concentrations 8 μg m–3 (SO2), 20 μg m–3 (NO2), 2 μg m–3 (O3) and minimal detectable absorptivity 5 × 10–7 cm–1 (aerosols) have been reached.

Measurement and modelling of thermal turbulence effects on FSO optical beams

Free Space Optics (FSO) is a data transmission technology using an optical beam going through the atmosphere. This communication technology has several indisputable advantages but also disadvantages. The one of the disadvantages are the thermal turbulences. This paper deals with the artificial thermal turbulences which affect the optical beam going from the commercial FSO head. The new against articles with similar topic is that this paper describes the turbulent effects spatially and not point wise as is often the case. At the same time this paper shows 3D modelling of turbulent effect on the FSO optical beam. The aim of the measurement was a demonstration of effects of the thermal turbulences and comparison the clear and turbulent atmosphere. The measurement was realized in four distances because the shape of optical beam was different in different distances.

Optical intensity scintillation in the simulated atmospherical environment

There are several parameters of the atmospheric environment which have an effect on the optical wireless connection. Effects like fog, snow or rain are ones of the effects which appears tendentiously and which are bound by season, geographic location, etc. One of the effects that appear with various intensity for the whole time is airflow. The airflow changes the local refractive index of the air and areas with lower or higher refractive index form. The light going through these areas refracts and due to the optical intensity scintillates on the detector of the receiver. The airflow forms on the basis of two effects in the atmosphere. The first is wind cut and flowing over barriers. The other is thermal flow when warm air rises to the higher layers of the atmosphere. The heart of this article is creation such an environment that will form airflow and the refractive index will scintillate. For the experiment, we used special laboratory box with high-speed ventilators and heating units to simulate atmospheric turbulence. We monitor the impact of ventilator arrangement and air temperature on the scintillation of the gas laser with wavelength 633 nm/15 mW. In the experiment, there is watched the difference in behavior between real measurement and flow simulation with the same peripheral conditions of the airflow in the area of 500 x 500 cm.

Studying the Interaction of Liquid and Solid in the Flow of Liquid in Annulus by CFD Analysis

This article is aimed to define the flow in the annulus. The shaft is deposited in a case which has at inlet and outlet recess. The rotor moves in the case. This movement can be divided into the rotation and precession. It is situation where the rotor rotates around own axis and together moves along the circle. The solution of the problem was the initiative in practice where this type of movement occurs in many components, e.g. sliding journal bearings. The fluid flows in the annulus due to the pressure gradient between inlet and outlet and together takes place rotational movement due to movement of the rotor. Between the liquid and the solid of an interaction which results in a change in the forces. The problem is solved by mathematical CFD solver ANSYS Fluent. Based on the characteristics of the problem has been defined corresponding to a mathematical model for the selected types of liquids - VG 32 mineral oil, VG 150 mineral oil and water. Individual variants of used liquids are compared with each other courses of forces acting on the rotor under the same boundary conditions.

Mathematical Modeling of Methane Combustion

Mathematical Modeling of Methane Combustion The paper presents the process of the creation of the mathematical model of methane turbulent combustion using ANSYS FLUENT 13.0 software. The decommissioned mathematical model for species transfer with chemical reaction is described, where burning is based on stoichiometric equations of perfect combustion. Work also analyzes the appropriateness of models dealing with the kinetics of burning and describes their mutual comparison.