• MATHEMATICAL MODELLING OF TECHNOLOGICAL PROCESSES AND SYSTEMS

    Modeling and simulation of forging processes

    Mathematical Modeling, Vol. 4 (2020), Issue 1, pg(s) 13-17

    Forging is an experience-oriented technology. The physical phenomena that describe the forging operations are difficult to express with quantitative relationships. In order to avoid the trail-and-error method, we use numerical simulations for studying the forging process. With the help of these simulations, the engineers are able to uncover the potential defects which may happen during the forging process. Concurrent Engineering (CE) helps in making the forging process more effective. In the CE system, each modification of the product represents a taxonomical relationship between specifications, outputs, and the concept it represents. In the study, the forging process of a disc shaped part is analysed. Thanks to numerical simulations it is determined that the dimensions of the billet are larger than needed. This resulted in overfilling the flash of the tool, thus the simulation was unsuccessful. After correcting the dimensions of the billet, the simulation ran with no interruptions.

  • Simulation of three-dimensional cavitation in radial divergent test section using different mass transfer models

    Mathematical Modeling, Vol. 3 (2019), Issue 1, pg(s) 21-24

    Cavitation is a phenomenon of liquid transition to vapour which occur at sudden drop in pressure. It can be studied experimentally using visualization techniques or numerically using numerical packages. In order to numerically predict cavitation Reynolds Averaged Navier Stokes equations and an additional transport equation for the liquid volume fraction can be used. In the additional transport equation mass transfer rate due to cavitation is modelled using different mass transfer models. In the presented paper cloud cavitation in radial divergent test section was studied numerically using three different widespread mass transfer models. The models used were Zwart, Kunz and Singhal mass transfer models. Zwart model is a native model of ANSYS CFX program while other two were implemented to the program. Steady state and transient RANS simulations were performed using the simulation program, standard k-e turbulence model and scalable wall functions. The results of numerical simulations were compared with the results of experimental measurements performed at the University of Grenoble. Based on the presented results we concluded that all mass transfer models correctly predict the area of cloud cavitation formation.

  • On a mathematical model of land-use change

    Mathematical Modeling, Vol. 2 (2018), Issue 4, pg(s) 153-155

    The paper is devoted to a mathematical model of land-use change proposed by Dobson et. al. We formulate and investigate some quantitative properties of the corresponding Cauchy problem. We construct a numerical algorithm for approximate solution of the problem and present some of the numerical results. Their meaning is explained and discussed.