scholarly journals ON INTERACTION OF A LIQUID FILM WITH AN OBSTACLE

2002 ◽  
Vol 7 (2) ◽  
pp. 327-342 ◽  
Author(s):  
A. Zemitis
Keyword(s):  
Liquid Film ◽  
Mathematical Models ◽  
Numerical Experiments ◽  
Impinging Jets ◽  
Numerical Results ◽  
Qualitative Behavior ◽  
Different Shapes ◽  
The Wire ◽  
The Difference

In this paper are discussed mathematical models for the liquid film generated by impinging jets. These models describe only the film shape under special assumptions about processes. Attention is stressed on the interaction of the liquid film with some obstacle. The idea is to generalize existing models and to investigate qualitative behavior of liquid film using numerical experiments. G.I. Taylor [Proc. R. Soc. London Ser. A 253, 313 (1959)] found that the liquid film generated by impinging jets is very sensitive to properties of the wire which was used as an obstacle. The aim of this presentation is to propose a modification of the Taylor's model, which allows to simulate the film shape in cases when the angle between jets is different from 180°. Numerical results obtained by discussed models give two different shapes of the liquid film similar as in Taylors experiments. These two shapes depend on the regime: either droplets are produced close to the obstacle or not. The difference between two regimes becomes larger if the angle between jets decreases. Existence of such two regimes can be very essential for some applications of impinging jets, if the generated liquid film can have a contact with obstacles.

Numerical Study of the Acoustic Efficiency of Sound-Absorbing Structures with Resonators of Various Forms

2018 ◽  
Vol 931 ◽  
pp. 158-163 ◽  
Author(s):  
Pavel V. Pisarev ◽  
Aleksandr N. Anoshkin ◽  
Karina A. Maksimova
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Numerical Solution ◽  
Numerical Experiments ◽  
Numerical Study ◽  
Experimental Studies ◽  
Acoustic Properties ◽  
Acoustic Characteristics ◽  
The Difference ◽  
Comparison Of The Results

The present work is devoted to a numerical study of the acoustic characteristics of cubic and folded resonators of sound-absorbing structures (SAS). In the process of work, a physical statement of the problem and a mathematical model for predicting the effective acoustic properties of the SAS cells are formulated. The validation of the developed mathematical models was carried out. During the comparison of the results of a numerical solution with experimental studies, the difference did not exceed 3%. Based on the results of the numerical experiments, the most effective resonators were identified, and recommendations on the design of the SAS on their basis were formulated.

Mathematical models of Gauss – Kruger projection for calculation of meridians conversion on the plane and scale of the image

2018 ◽  
Vol 934 (4) ◽  
pp. 2-7
Author(s):  
P.A. Medvedev ◽  
M.V. Novgorodskaya
Keyword(s):  
Mathematical Models ◽  
Analytical Methods ◽  
Theoretical Studies ◽  
Spherical Trigonometry ◽  
Cylindrical Projection ◽  
Rectangular Coordinates ◽  
In Series ◽  
Observational Errors ◽  
The Difference

This work contains continued research carried out on improving mathematical models of the Gauss-Krueger projection in accordance with the parameters of any ellipsoid with the removal of points from the axial meridian to l ≤ 6° . In terms of formulae earlier derived by the authors with improved convergence for the calculation of planar rectangular coordinates by geodesic coordinates, the algorithms for determining the convergence of meridians on the plane and the scale of the image are obtained. The improvement of the formulae represented in the form of series in powers of the difference in longitudes was accomplished by separating spherical terms in series and then replacing their approximate sums by exact expressions using the formulae of spherical trigonometry. As in previous works published in this journal [7, 8], determining the sums of the spherical terms was carried out according to the laws of the transverse-cylindrical projection of the sphere on the plane. Theoretical studies are given and formulae are proposed for estimating the observational errors in the results of the derived algorithms. The maximum of observational errors of convergence of meridians and scale, proceeding from the specified accuracy of the determined quantities was established through analytical methods.

Experimental and Numerical Study on Grinding Temperature during Surface Grinding with Different Cooling Methods

2009 ◽  
Vol 416 ◽  
pp. 514-518 ◽  
Author(s):  
Qing Long An ◽  
Yu Can Fu ◽  
Jiu Hua Xu
Keyword(s):  
Numerical Study ◽  
Specific Energy Consumption ◽  
Ground Surface ◽  
Numerical Results ◽  
Surface Grinding ◽  
Grinding Temperature ◽  
Air Jet ◽  
The Difference ◽  
High Specific Energy ◽  
Cooling Methods

Grinding, characterized by its high specific energy consumption, may generate high grinding zone temperature. These can cause thermal damage to the ground surface and poor surface integrity, especially in the grinding of difficult-to-machine materials. In this paper, experimental and fem study on grinding temperature during surface grinding of Ti-6Al-4V with different cooling methods. A comparison between the experimental and numerical results is made. It is indicated that the difference between experimental and numerical results is below 15% and the numerical results can be considered reliable. Grinding temperature can be more effectively reduced with CPMJ than that with cold air jet and flood cooling method.

NUMERICAL SOLUTION OF TWO-DIMENSIONAL PROBLEMS OF THERMOVISCOELASTICITY

2021 ◽  
Vol 335 (1) ◽  
pp. 60-64
Author(s):  
M. Bukenov ◽  
Ye. Mukhametov
Keyword(s):  
A Priori ◽  
Elastic Collision ◽  
Qualitative Behavior ◽  
Stress Profile ◽  
Two Dimensional ◽  
A Priori Information ◽  
Deformable Solids ◽  
Methods Of Calculation ◽  
The Difference ◽  
Priori Information

This paper considers the numerical implementation of two-dimensional thermoviscoelastic waves. The elastic collision of an aluminum cylinder with a two-layer plate of aluminum and iron is considered. In work [1] the difference schemes and algorithm of their realization are given. The most complete reviews of the main methods of calculation of transients in deformable solids can be found in [2, 3, 4], which also indicates the need and importance of generalized studies on the comparative evaluation of different methods and identification of the areas of their most rational application. In the analysis and physical interpretation of numerical results in this work it is also useful to use a priori information about the qualitative behavior of the solution and all kinds of information about the physics of the phenomena under study. Here is the stage of evolution of contact resistance of collision – plate, stress profile.

NUMERICAL REEXAMINATION OF SUPERSYMMETRIC AND NONSUPERSYMMETRIC SU(5)-LIKE GRAND UNIFIED MODELS

1989 ◽  
Vol 04 (10) ◽  
pp. 2531-2559 ◽  
Author(s):  
DARIUSZ K. GRECH
Keyword(s):  
Numerical Analysis ◽  
Numerical Computation ◽  
Numerical Results ◽  
Yukawa Couplings ◽  
Loop Level ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Supersymmetric Particles ◽  
The Difference

The significance of numerical analysis in both nonsupersymmetric and supersymmetric Grand Unified Theories is pointed out. The exact analytical and numerical analysis we present shows a need of larger corrections to the values of unifying parameters, i.e. sin 2 θw, Mx, τp than those often quoted in literature. When an unmodified nonsupersymmetric version of SU(5) is considered we show that numerical computation allows some of the models still to be experimentally admissible. The difference between analytical and numerical results for the supersymmetric SU(5) model is also stressed. In particular, corrections due to the mass threshold of additional generations or supersymmetric particles are calculated both analytically and numerically at the two-loop level. We found them far more important for the final values of sin 2 θw, Mx and τp than the effects of Higgs-Yukawa couplings between scalars and fermions.

scholarly journals Weak solvability of the unconditionally stable difference scheme for the coupled sine-Gordon system

2020 ◽  
Vol 25 (6) ◽  
pp. 997-1014
Author(s):  
Ozgur Yildirim ◽  
Meltem Uzun
Keyword(s):  
Difference Scheme ◽  
Numerical Method ◽  
Existence And Uniqueness ◽  
Numerical Experiments ◽  
Finite Difference Schemes ◽  
Order Of Accuracy ◽  
Unconditionally Stable ◽  
First Order ◽  
The Difference ◽  
Weak Solvability

In this paper, we study the existence and uniqueness of weak solution for the system of finite difference schemes for coupled sine-Gordon equations. A novel first order of accuracy unconditionally stable difference scheme is considered. The variational method also known as the energy method is applied to prove unique weak solvability.We also present a new unified numerical method for the approximate solution of this problem by combining the difference scheme and the fixed point iteration. A test problem is considered, and results of numerical experiments are presented with error analysis to verify the accuracy of the proposed numerical method.

scholarly journals Design of Large Connectors of Overhead Power Lines

2018 ◽  
Vol 61 (5) ◽  
pp. 432-439 ◽  
Author(s):  
M. A. Korotkevich ◽  
N. V. Prokofieva
Keyword(s):  
Power Transmission ◽  
Power Lines ◽  
Traditional Theory ◽  
Engineering Structures ◽  
Cross Sectional ◽  
Flexible Filament ◽  
Nominal Voltage ◽  
The Wire ◽  
The Difference ◽  
Overhead Power Lines

It is found that the voltage at the lowest points of the wire or cable sag and at the points of their suspension on the pillars in the same span, determined in accordance with the properties of a perfectly flexible filament (similar to which the wires and cables are located in the span), differ slightly, and taking the difference of the mentioned values into account is only of methodologycal importance. The article presents the results of the calculation of wire and cable sag of large spans of power transmission line of 500 m or more length using both the traditional theory of the catenary line and the theory of equal resistance, when the cross-sectional area of a wire or cable, proportional to their tension, is considered variable in the span length, which provides the same probability of breaking them at any point of the span. When calculating the wires and cables in normal and emergency conditions, the largest sags are determined, which take place either at a higher ambient temperature or at a load of the wire with ice. The wire must be mounted in such a way as to ensure the normalized permissible dimensions to crossed engineering structures, water barriers or land, that are determined depending on the nominal voltage of the line. It is noted that the values of the wire and cable sags determined using the theory of the catenary line for the transition spans are less (although slightly) as compared to the data obtained on the basis of the theory of the equal resistance circuit. This must be taken into account in the design process.

scholarly journals Recent variations of calving glaciers in Patagonia, South America, revealed by ground surveys, satellite-data analyses and numerical experiments

1995 ◽  
Vol 21 ◽  
pp. 297-303 ◽  
Author(s):  
Renji Naruse ◽  
Masamu Aniya ◽  
Pedro Skvarca ◽  
Gino Gasassa
Keyword(s):  
South America ◽  
Mass Balance ◽  
Numerical Experiments ◽  
Satellite Images ◽  
Balance Model ◽  
Equilibrium Line Altitude ◽  
Simple Mass ◽  
Surface Profiles ◽  
The Difference ◽  
Altitudinal Distributions

Large retreats were revealed for most glaciers in Patagonia, South America, by analyzing satellite images and air photographs. For example, Glaciar O’Higgins retreated 13 km during 41 years from 1945 to 1986 and Glaciar Upsala retreated about 3 km between 1968 and 1990. During the 41 years former period, however, the southern tongue of Glaciar Pio XI advanced by up to 8.5 km and Glaciar Moreno remained almost in a steady state. Considerable ice-thinning rates, from 3.0 to 11 ma−1, were measured by surveying surface profiles in the ablation areas of Tyndall and Upsala glaciers, respectively, during the period from 1985 (or 1990) to 1993. The ice thickness of Glaciar Moreno, however, has changed very little. Numerical experiments using a simple mass-balance model show that a 100 m rise in the equilibrium-line altitude due to climatic change would result in about a 200–350 m rise in the frontal altitude at Glaciar Upsala corresponding to a retreat of 5–8 km, while it would cause only about a 70–100 m rise at Glaciar Moreno. The large difference between these two neighbouring glaciers results from the difference in contributions of the calving amount to the total mass balance, as well as the difference in the altitudinal distributions of drainage areas.

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