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

A group of numerical methods suitable for describing the propagation of light in a Photonic Crystal Fiber (PCF) are discussed. PCFs can be classified according to the mechanism of light propagation. The methodology of the analysis is briefly reviewed to understand how changing the different physical parameters of the fiber and the design affects its optical properties. By analyzing the systematic studies presented, a design with the desired optical fiber properties can be realized.
PCFs can be made from just one material with two-dimensional photonic crystals or periodic arrays of air holes parallel to the fiber axis to form a shell and core shape. Several types of PCFs have been considered. The mechanism for trapping light in the fiber core is explained. The use of the wave methods for electromagnetic field analysis is discussed. The application of variation principles and weighted residual methods is shown. The advantages of the finite element method (FEM) are indicated. The vector FEM for obtaining the modes in photonic crystal fibers is considered.

The technological progress in computer technologies gave rise to new possibilities and progresses for numerical and iterative methods. As being one of the computational studies, computational fluid dynamics is highly related to today’s advances. There are various types of methods and algorithms developed to model complex phenomena of fluid flow. In this study, we will introduce a new, still in development stage, CFD code with a pre-processor and a solver. Our research is focused on developing and studying a CFD code for mainly internal flows. Laminar and turbulent 2-dimensional flows can be analyzed using the software. The code is equipped with a graphical user interface (GUI) to make it simple to use. The GUI has the all-necessary components to define and analyze a fluid flow problem. We used an open-source post processor in order to visualize flow data and linked it to GUI, so the resulting software is a complete CFD package. The entire software is written using Python which has an easy code structure and rich code libraries. In order to decrease the time for convergence, code is modified with Numba and Cython libraries. To confirm accuracy of the solver, various basic test cases from the literature such as backward facing step flow, impinging jet flow, flow across a square cylinder, lid driven cavity flow are tested for both laminar and turbulent flows and the results was described in detail.

For simulation of processes of compaction or forging of products from powder materials, a method of permeable elements is proposed. The essence of the method is to use elements whose shape is regulated in advance, and, unlike the finite element method, where the elements coincide with the material volumes and their masses are unchanged, here the masses elements are variable, and material can flow between adjacent cells. Examples of using the method for modeling the processes of forging of porous preforms in closed and open dies, as well as in a closed die with a compensation cavity, are presented.