NUMERICAL REALIZATION OF THE ALGORITHM FOR SOLVING THE TASKS OF HYDROPHYSICS IN THE AREA WITH COMPLEX GEOMETRY

2019 ◽  
pp. 3-12
Author(s):  
A. I. Sukhinov ◽  
A. E. Chistyakov ◽  
V. N. Litvinov ◽  
A. V. Nikitina
Keyword(s):  
Numerical Solution ◽  
Hydrodynamic Model ◽  
Complex Shape ◽  
Complex Geometry ◽  
Model Problem ◽  
Computational Grids ◽  
Calculation Error ◽  
Physical Processes ◽  
Hydrodynamic Processes ◽  
Rectangular Grids

The work is devoted to the development and numerical implementation of an algorithm for solving the problem of modeling the process of hydrophysics, describing the transport of polluting biogenic substances in a complex shape. The velocity field of the water flow, calculated according to the hydrodynamic model of the Sea of Azov, is used in the model of transport of polluting nutrients as input data. To test the accuracy of the numerical solution of the hydrodynamic model problem, a test problem of viscous fluid flow between two coaxial semicylinders is used. To solve the interrelated problems of hydrophysics, including a model of hydrodynamic processes and a model of transport of polluting nutrients, rectangular grids are used, taking into account the “fullness” of the cells. The approximation of the problem in time is made on the basis of splitting schemes for physical processes. To assess the accuracy of the numerical solution of hydrodynamic problems, an analytical solution describing the Couette–Taylor flow is used as a reference. The simulation was carried out on a sequence of thickening computational grids with dimensions: 11×21, 21×41, 41×81 and 81×161 nodes in the cases of a smooth and stepped border. To increase the smoothness of the solution, grids were used that take into account the “fullness” of the cells. In the case of a stepwise approximation of the interface between two media, the calculation error reaches 70 % of the error solution of the problem. When using grids that take into account the “fullness” of cells, the error in the numerical solution of model problems of hydrodynamics, caused by the approximation of the boundary, does not exceed 6 % of the error solution of the problem. The example shows that the fragmentation of the grid by 8 times for each of the spatial directions does not lead to an increase in the accuracy that solutions obtained on the grids, which take into account the “fullness” of the cells, possess.

scholarly journals One task of routing jobs in high radiation conditions

2021 ◽  
Vol 58 ◽  
pp. 94-126
Author(s):  
A.G. Chentsov ◽  
A.A. Chentsov ◽  
A.N. Sesekin
Keyword(s):  
Dynamic Programming ◽  
Numerical Solution ◽  
Model Problem ◽  
Optimal Solution ◽  
High Radiation ◽  
Dose Load ◽  
Route Problem ◽  
Precedence Conditions ◽  
Sequential Bypass ◽  
Radiation Conditions

The problem of sequential bypass of megalopolises is investigated, focused on the problem of dismantling a system of radiation hazardous objects under constraints in the form of precedence conditions. The radiation impact on the performers is assessed by the doses received during movements and during the performance of dismantling works. The route problem of minimizing the dose load of workers carrying out dismantling in one or another sequence of operations is considered. The procedure for constructing an optimal solution using a variant of dynamic programming is investigated. On this basis, an algorithm is built, implemented on a PC. Examples of the numerical solution of a model problem for the minimum dose load are given.

Analysis of Physical Processes in a Holding Electrical Furnace

2014 ◽  
Vol 698 ◽  
pp. 188-192
Author(s):  
Victor Timofeev ◽  
Sergey Perfilyev
Keyword(s):  
Aluminum Alloys ◽  
Present Article ◽  
Automated Design ◽  
Physical Processes ◽  
Electrical Furnace ◽  
Hydrodynamic Processes

The present article describes the results of automated design and analysis of electromagnetic, thermal and hydrodynamic processes in a holding electrical furnace for preparation of aluminum alloys. The availability of a parameter model enables to design a furnace of any given capacity in quick time and carry out an analysis of physical processes in it.

Analysis and numerical solution of dynamic Jiles–Atherton model applied to hysteresis modeling for giant magnetostrictive materials

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ce Rong ◽  
Zhongbo He ◽  
Guangming Xue ◽  
Guoping Liu ◽  
Bowen Dai ◽  
...  
Keyword(s):  
Numerical Solution ◽  
Numerical Computation ◽  
Model Parameters ◽  
Calculation Error ◽  
Rational Form ◽  
Modified Model ◽  
Content Type ◽  
Magnetostrictive Materials ◽  
Giant Magnetostrictive Materials ◽  
Computation Scheme

PurposeOwing to the excellent performance, giant magnetostrictive materials (GMMs) are widely used in many engineering fields. The dynamic Jiles–Atherton (J-A) model, derived from physical mechanism, is often used to describe the hysteresis characteristics of GMM. However, this model, despite cited by many different literature studies, seems not to possess unique expressions, which may cause great trouble to the subsequent application. This paper aims to provide the rational expressions of the dynamic J-A model and propose a numerical computation scheme to obtain the model results with high accuracy and fast speed.Design/methodology/approachThis paper analyzes different published papers and provides a reasonable form of the dynamic J-A model based on functional properties and physical explanations. Then, a numerical computation scheme, combining the Newton method and the explicit Adams method, is designed to solve the modified model. In addition, the error source and transmission path of the numerical solution are investigated, and the influence of model parameters on the calculation error is explored. Finally, some attempts are made to study the influence of numerical scheme parameters on the accuracy and time of the computation process. Subsequently, an optimization procedure is proposed.FindingsA rational form of the dynamic J-A model is concluded in this paper. Using the proposed numerical calculation scheme, the maximum calculation error, while computing the modified model, can remain below 2 A/m under different model parameter combinations, and the computation time is always less than 0.5 s. After optimization, the calculation speed can be enhanced with the computation accuracy guaranteed.Originality/valueTo the best of the authors’ knowledge, this paper is the first one trying to provide a rational form of the dynamic J-A model among different citations. No other research studies focus on designing a detailed computation scheme targeting the fast and accurate calculation of this model as well. And the performance of the proposed calculation method is validated in different conditions.

scholarly journals Numerical Simulation of Fluid Flow and Combustion in Gas Turbine Combustors

1993 ◽  
Author(s):  
Inge R. Gran ◽  
M. C. Melaaen ◽  
F. Magnussen
Keyword(s):  
Gas Turbine ◽  
Complex Geometry ◽  
Reacting Flows ◽  
Staggered Grid ◽  
Computational Grids ◽  
Turbulent Reacting Flows ◽  
Combustion Chambers ◽  
Gas Turbine Combustors ◽  
Elliptic Differential Equations ◽  
Finite Volume Approach

The finite-volume approach together with body-fitted curvilinear non-orthogonal coordinates and a non-staggered grid arrangement is used for investigating turbulent reacting flows inside gas turbine combustion chambers. The computational grids are generated by solving elliptic differential equations, permitting an accurate description of the complex geometry of commercial gas turbine combustors. Different combustion models are briefly discussed with a view to their suitability for practical combustor predictions. The k-ε model and the Eddy Dissipation Concept are selected to account for the turbulent combustion in the present study. The governing equations and coordinate transformations needed to derive the discretized equations are reviewed. One isothermal and two combusting flow fields are calculated. The calculations are in reasonable agreement with measurements, but the results should be improved by grid refinement and by using a better turbulence model.

Direct Digital Additive Manufacturing and Cyber-Enabled Manufacturing Systems

2012 ◽  
Author(s):  
Khershed P. Cooper
Keyword(s):  
Additive Manufacturing ◽  
Manufacturing Systems ◽  
Complex Geometry ◽  
Basic Research ◽  
Naval Research ◽  
Physical Processes ◽  
Physical Systems ◽  
Office Of Naval Research ◽  
And Control ◽  
Manufacturing Problems

The technology of direct digital additive manufacturing (D2AM) has received considerable attention in recent months. Several government agencies and commercial interests are planning to explore D2AM to find solutions to manufacturing problems. The attraction of D2AM is the benefit of rapidly producing without fixtures or tools or human intervention customized objects of complex geometry not possible by traditional methods. The interest in D2AM ranges from fabrication of critical, high value aerospace metallic components to fabrication of objects having an organic look or as nature would have intendedi. For D2AM to be commercially accepted, it must reliably and predictably make products. It must achieve consistency in reproducibility across relevant D2AM methods. The Office of Naval Research (ONR) has launched a new basic research program, known as Cyber-enabled Manufacturing Systems (CeMS). The long-range goal of the program is to achieve the level of control over D2AM processes for industrial acceptance and wide-use of the technology. This program will develop measuring, sensing and control models and algorithms for D2AM by harnessing principles underpinning cyber-physical systems (CPS) and fundamentals of physical processes. This paper describes the challenges facing D2AM and the CeMS program goals to meet them.

scholarly journals Optimal Gyrodine Rotor Shape in the Class of Conical Bodies

2021 ◽  
pp. 69-81
Author(s):  
Andrey Biryuk ◽  
Mikhail Drobotenko ◽  
Igor Ryadchikov ◽  
Alexander Svidlov
Keyword(s):  
Angular Momentum ◽  
Numerical Solution ◽  
Poisson Ratio ◽  
Stress Fields ◽  
Constant Thickness ◽  
Calculation Error ◽  
Angular Rotation ◽  
Axis Of Rotation ◽  
Rotor Shape ◽  
Two Parameters

The problem is to find the optimal shape of the gyrodine rotor and its angular rotation speed that maximizes the angular momentum relative to the axis of rotation at a fixed radius, mass and material of the rotor, taking into account the final strength of the material. The gyrodine rotor is a body of revolution, the thickness of which depends only on the distance r to the axis of rotation, r ∈ [0,R], where R is the radius of the rotor. The rotor surface is defined by rotating the curves z = ±z(r) around the axis. When the rotor is spinning, it undergoes deformation due to centrifugal forces. Normal stress fields appear: radial and annular. Assuming the rotor to be thin, deformations can be described by the functions of the radial displacement of the rotor points u(r). Stress fields can be expressed in terms of this function. The functions u(r) and z(r) are related by the equation of the elastically deformed state. This equation is supplied with the boundary conditions for the absence of radial stresses at r = R and the condition for the absence of displacement on the axis of rotation u(0) = 0. Using the numerical solution of the equation, the problem is solved for the class of conical rotors z(r) = a + br with two parameters a and b. The numerical method is used due to the fact that even in this relatively simple case the problem cannot be solved analytically. Several integrable cases are used to analyze the calculation error in the numerical solution of the problem. The dependence of the problem on the Poisson ratio μ ∈ (−1.1) is investigated, with the remaining parameters fixed. The gain in the angular momentum relative to a rotor of constant thickness is compared. The optimal steel conical rotor (μ = 0.3) is 2.068 times thicker at the center than at the edge. Its advantage in the angular momentum over the rotor of constant thickness is 3.2 %.

POROSITY OF COMPOSITE STRUCTURES BASED ON 3D-PRINTED FRAMES IMPREGNATED WITH EPOXY RESIN

2021 ◽  
Vol 1 (142) ◽  
pp. 131-139
Author(s):  
Yuliya A. Lopatina ◽  
◽  
Vyacheslav A. Denisov
Keyword(s):  
3D Printing ◽  
Epoxy Resin ◽  
Composite Structures ◽  
Epoxy Resins ◽  
Complex Shape ◽  
Complex Geometry ◽  
Research Purpose ◽  
Second Stage ◽  
3D Printed ◽  
The Cost

In the designs of modern machines, more and more polymer parts are used, at the same time, there is a problem of their quick replacement in case of failure. Reducing the cost and repair time can be achieved by using 3D printing by FDM method, but such parts do not always demonstrate the necessary strength. To improve their mechanical properties, a method of their impregnation after printing in epoxy resins was previously proposed. (Research purpose) The research purpose is in studying the dependence of the porosity of composite structures based on 3D-printed frames impregnated with resin on the parameters of their manufacture. (Materials and methods) Authors used samples for the first stage of the work, which are 3D-printed cylinders with different wall thicknesses and internal geometries, impregnated with ED-20 epoxy resin. The samples were cut in several sections and the number of pores in these sections was calculated. The second stage of the experiment was to evaluate the porosity of a part of complex geometry. (Results and discussion) With an increase in the percentage of filling and thickening of the wall in 3D printing, there is a tendency to reduce the number of pores. With a less dense filling of the frame and a thinner wall, the resin is worse retained in the product and partially flows out after impregnation. The best filling of a part of a complex shape was observed when it was cured in the position of the massive part up. (Conclusions) For the production of high- quality composite parts based on 3D-printed frames impregnated with epoxy resin, it is recommended to choose the largest possible percentage of filling during 3D printing and strive to position the part during the curing process after impregnation with the massive part up.

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