International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

We present and explain the mathematical apparatus used in a numerical simulation model created with АNSYS СFX Software. The purpose of the model is to perform computations of fog parameters in different points of artificially generated fog sprays, which are then used to calibrate a novel type of fog sensors. By changing the distance between the nozzle and the measuring laser beam of the sensor, we can assess how the number flow rate and diameter distribution of fog droplets are varied within in the spray. This work is related to improving European security by introducing systems for quick counteraction to terrorist attacks, industrial accidents and natural disasters. These systems use artificial fog generation to collect and deposit on the ground harmful aerosols dispersed in air, especially CBRN agents. Our newly developed fog sensors operate on the basis of the electromagnetic echo effect to control the decontamination process. In order to optimize the work of the sensors, it is crucial to investigate fogs and their ability to absorb harmful substances from air. The most important fog parameters that influence the efficiency of the cleaning process are the number of droplets and their size.

Not all the properties of structured surfaces can be predicted just through using stationary solutions. Hydrophilic and hydrophobic qualities distinctly manifest themselves when surface contacts with mobile liquid; besides, shape of surface projections could variously influence flow velocity in different directions forming turbulences behind projections (even cavitation zones if flow is very fast). The following properties of liquids are particularly important for these processes: dynamic and kinematic viscosity, density, flow velocity and characteristic flow size, which represents itself contact surface relation to cross-sectional area. Relationships between these parameters characterize flowability of the particular substance and can be expressed as Reynolds number. Solutions of kinetic equations could be helpful to develop understanding on particular fluid’s flowability in the close vicinity of the surface.
Examples discussed in this paper can be used not only in nano- and microstructures related research but also for high school and university students training in physics and natural sciences. Comprehension development about flow rate diferences in various distances from tube walls should be considered as one of problems for successful acquiring of hydrodynamics topics. Even use of transparent tubes is not helpful enough for appropriate demonstration of tinted liquid speed distribution in flow’s cross-sectional area – laminar flow when Reynolds number value is low and turbulent flow when it is high.

Nano-level surface processing is becoming increasingly important in the development of modern materials. Laser technology allows to change the processing parameters in a wide range and achieve the desired surface properties – hydrophilic and hydrophobic for various fluids. In such circumstances, the benefit of any researcher would be to provide software that can quickly and visibly see and measure the shape, size and configuration of nano and microstructures to be obtained. It is especially important that the obtained results in the form of 3D graphs allow us to see the evolutionary trends of surface nanostructures and help to decide on changes in the processing parameters. The researcher would be given the opportunity to input a wide variety of parameters – laser wavelength, pulse power, polarization angle, pulse frequency, pulse duration, processing time or number of impulses per coordinate – and the result obtained in a short time would serve to better understand common trends and help to make an informed decision for the actual processing parameters to be used in the experiment.

In the present paper, the model of nanostructure formation on solid surface by microsecond laser pulses melting the material is described. It is shown that typical size of surface nanostructure formed depends on laser wavelength, pulse energy, pulse repetition rate, and pulse duration. Within present work a series of 6 experiments devoted to direct laser nanostructuring of titanium (Ti) and copper (Cu) surfaces is carried out. Besides, the effects of nanoroughness on the contact and sliding angles on hydrophilic surfaces were studied theoretically and experimentally.