viscosity

Understanding the mechanics of a turbulent boundary layer is important, since in most practical problems it is the turbulent boundary layer that is primarily responsible for the surface shear force or surface resistance. The velocity distribution in a turbulent boundary layer on a flat plate is considered parallel to the flow. It is important to know the correlations between the boundary layer thickness and shear stress. Therefore, the problem of controlling the flow in a boundary layer on a flat plate is one of the important problems of boundary layer mechanics.

In fluid and gas mechanics, a subject that has been the focus of considerable scholarly attention is the modeling of flow phenomena on streamlined surfaces. These surfaces, which are typically installed in a parallel orientation to the direction of the free stream, play a pivotal role in the study of fluid dynamics. The boundary layer theory represents a pivotal branch of fluid dynamics, given the airflow plate is characterized by a high Reynolds number of airflow velocity entering the plate's plane surface contexts.

The suspension oligomerization of the unsaturated hydrocarbons of the C9 fraction of liquid by-products of diesel fuel pyrolysis initiated by N-(tert-Butylperoxymethyl)-4- chloroaniline was investigated. The influence of reaction conditions (reaction temperature and time, mixing intensity,  dispersed phase content, initiator concentration) on the yield and physico-chemical characteristics of hydrocarbon resins was determined. The optimal reaction conditions were selected.

The current problem of the production and processing of heavy high-viscosity oils in Ukraine and the world has been considered. It has been established that the main reserves of heavy high-viscosity crude oils in the world are located in South and North America, in the Middle East, as well as in Ukraine in the eastern regions. An analysis of various classifications of heavy high-viscosity oils, which are used both in Ukraine and in the world, was carried out. The main extraction methods of heavy high-viscosity oils were considered, in particular, quarry, mine, and well extraction methods.

The article presents a three-dimensional mathematical model of the gas filtration process in porous media and a numerical algorithm for solving the initial-boundary value problem.  The developed model is described using the nonlinear differential equation in partial derivatives with the appropriate initial and boundary conditions.  The proposed mathematical apparatus makes it possible to carry out hydrodynamic calculations taking into account changes in the main factors affecting the process under consideration: permeability, porosity, and thickness of layers, gas recovery coefficient, visc

Cumulative experience in the field of development of bioactive glass ceramics for bone implants and methods of strengthening thereof have been analyzed. Compositions were selected and model glasses were synthesized, the relationship between viscosity and crystallization ability of glass ceramics has been studied. Composite materials based on the glass ceramics and zirconia have been synthesized, their mechanical properties studied, and feasibility of their use in the creation of bone implants has been established.

An approach to water emulsions modification with structure forming additives, namely cellulose esters, is proposed in the article. Influence of the film former origin on the system rheological properties at different shear-strain rates was examined. Structural and mechanical, as well as rheological properties of the studied systems were determined. The results confirm that hydroxyethylcellulose has a greater structure forming effect in comparison with carboxymethylcellulose.

We propose an approach to the preparation of viscoelastic systems based on chitosan without crosslinking agents. It is the formation of an additional network of physical links by introducing a low molecular weight modifier – ethanol or glycerol. It turns out that gelation of chitosan in the solution is accompanied by the formation of additional meshes of physical links, nodes or aggregates of chitosan macromolecules formed in a mixed solvent of acetic acid-water-glycerol or acetic acid-waterethanol.

The experimental researches of regulation of rheology properties of clay mixture by using to clays the additives of mineral and organiccontained electrolytes in ceramics technology are given.  Подано експериментальні дослідження регулювання реологічних властивостей шлікерів за допомогою використання до глин добавок мінеральних і органовмісних електролітів у технології кераміки.