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

The objective of the simulations is to calculate the total resistance and visualize the flow around a bare hull of a boat motion in deep and shallow water. Ship resistance is an important issue for ensuring smooth propulsion in various speeds in open sea and especially in the increasing influence of shallowness. Subcritical speed range in open shallow water is the main interest regime. A limited number of cases in critical and supercritical speed regions are applied in computations for comparison. For the full-scale bare ship-shape body resistance tests, computational fluid dynamics techniques and SST k-omega turbulence viscous model were employed. All calculations were carried out considering the influence of the free surface effect in a fluid. For convenience of mesh generation, an automated structured polyhedral meshing was adopted for the delicate curved surface and the domain. CFD solver interFoam – OpenFOAM, is applied to execute all computations in this article. The numerical model was initially built in FreeCAD, an open computer aided design (CAD) software and discretized in the cfMesh, a library implemented on top of the OpenFOAM framework. Post-processing is performed within ParaView, an application for scientific visualization. All software is free.

The prediction of maneuverability is a classic problem in ship hydrodynamics. Likewise, ship motions in restricted waters have been studied for a long time. It is an indisputable fact that full-scale or model tests of the respective ship meet IMO requirements and provide the necessary information for the maneuverability of the ship in deep unconfined waters. However, they are unable to provide practical insight into understanding of ship maneuverability in shallow water, as the maneuvering behavior of a ship in such areas differs significantly. Ship maneuvering in coastal areas and harbor approaches, where space is limited, movement speeds are low, and traffic heavier requires deeper researching. The aim of the present work is to predict the hydrodynamic derivatives in the mathematical model of the maneuvering of ship in shallow waters based on CFD programs with free access like FreeCAD, OpenFOAM and ParaView.
The sequence of solving the task is described with details in this work:
1. Generating the shape of the studied body 2. Creating the domains around the experimental body, sizes and boundaries
3. Defining the continuum, areas and subareas of study, and boundary conditions 4. Generation of the computational grid
5. Defining the continuum – physical models 6. Selection of the calculation algorithm 7. Substances modeling 8. Motion modeling.
9. Modeling of currents and energy 10. Flow turbulence modeling.
Results have been obtained for the linear hydrodynamic derivatives in the mathematical model for the maneuvering motion of a ship.
They are compared with available experimental and theoretical data in the literature.

In this paper, the impact of wind forces on human bodies is shown. Like many meteorological phenomena, the influence of wind energy applied to human bodies is inevitable which comes into the spotlight of the scientist only when the wind becomes violent and extremely disturbing. Based on weather and observations in February 2019, abnormal wind characteristics in Albania are evidenced. On February 23, 2019, a very special situation in the Northern part of Albania, the region of Puka, with extreme values of wind parameters causing the phenomenon of “wind gust”, leading to a series of material damage and loss of human life, is evidenced. Researchers and predictors need scientific information on the impact of strong winds applied on the human body for specific conditions. Wind speed values in this region of the northern part of our country set records reaching extremely values (30 ÷ 35) ms-1 on the ground level. Taking a cue from this unprecedented situation, the effect of strong winds on the determination of aerodynamic forces acting on the human body using numerical simulations has been studied and so far, well investigated. For this study, we considered a human body with a height of 172cm. The investigation takes into account two different positions against the wind, frontal and lateral position traversed by wind speeds levels of 20m/s, 30m/s, and 40 m/s. The study concluded that strong winds can exhibit unimaginable and unaffordable forces, leading to fatal consequences for human life.

The main scope of this paper is to fully integrate simulation from open source CFD software with the Matlab App Designer program. The OpenFOAM-Matlab CFD interface allows one to conveniently setup fully turbulent incompressible Reynolds Averaged Navier-Stokes (RANS) CFD case all within an easy to use graphical user interface (GUI). Highlighting built-in CAD tools to create geometry (STL) for automatic mesh generation to OpenFOAM case file as well as a solution with post-processing and visualization with ParaView. Also, the cross-platform OpenFOAM CFD interface for MATLAB should allow the user to rapidly design the spiral casing in an engineering manner as an illustrative platform and coordinator between the inputs chosen by the user and the results which are displayed after calculations. Furthermore, the GUI should be a very flexible and user-friendly platform for spiral casing design according to the efficiency and static pressure recovery coefficient as well.

Numerical algorithm for calculating thin film cavitational effects is presented in this paper. Cavitation is a common phenomenon in diverging parts of thin film contacts, such as: journal bearings, ball bearings, seals, etc. Locating and calculating cavitational effects is very important for their applicability, efficiency and safety. The thin film flow solver based on the Reynolds equation, together with cavitation algorithm is implemented using the Finite Area Method inside the OpenFOAM framework. OpenFOAM is an open source C++ toolbox for computational fluid dynamics (CFD). The Finite Area Method is a two-dimensional counterpart of the Finite Volume Method, used for discretising partial differential equations over curved surfaces. Discretisation is performed on user selected patches of computational mesh, with values calculated at face centres and fluxes calculated at edge centres of each finite area face. Reynolds equation is a 2D partial differential pressure equation used for calculating thin film flows between two surfaces in relative motion, with the following assumptions: fluid viscous forces dominate over body, inertia and surface tensions forces; fluid film curvature can be neglected; variation of pressure across the fluid film is negligibly small. The implemented cavitation algorithm is capable of capturing both rupture and reformation boundaries during cavitation, therefore it is considered to be mass conserving. The implemented solver is validated on three test cases: single parabolic slider (1D), twin parabolic slider (1D) and microtexture pocket bearing (2D).