Elliptic Complex Geometry and Oka Theory

Abstract “Hydroplaning characteristics” is one of the key functions for safe driving on wet roads. Since hydroplaning depends on vehicle velocity as well as the tire construction and tread pattern, a predictive simulation tool, which reflects all these effects, is required for effective and precise tire development. A numerical analysis procedure predicting the onset of hydroplaning of a tire, including the effect of vehicle velocity, is proposed in this paper. A commercial explicit-type FEM (finite element method)/FVM (finite volume method) package is used to solve the coupled problems of tire deformation and flow of the surrounding fluid. Tire deformations and fluid flows are solved, using FEM and FVM, respectively. To simulate transient phenomena effectively, vehicle-body-fixed reference-frame is used in the analysis. The proposed analysis can accommodate 1) complex geometry of the tread pattern and 2) rotational effect of tires, which are both important functions of hydroplaning simulation, and also 3) velocity dependency. In the present study, water is assumed to be compressible and also a laminar flow, indeed the fluid viscosity, is not included. To verify the effectiveness of the method, predicted hydroplaning velocities for four different simplified tread patterns are compared with experimental results measured at the proving ground. It is concluded that the proposed numerical method is effective for hydroplaning simulation. Numerical examples are also presented in which the present simulation methods are applied to newly developed prototype tires.

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NUMERICAL STUDY OF DETONATION PROPAGATION IN VISCOUS TURBULENT FLOW IN A DUCT

PROGRESS IN DETONATION RESEARCH ◽

10.30826/icpcd12a12 ◽

2020 ◽

Author(s):

V. A. SABELNIKOV ◽

◽

V. V. VLASENKO ◽

S. BAKHNE ◽

S. S. MOLEV ◽

...

Keyword(s):

Complex Geometry ◽

Numerical Study ◽

Navier Stokes ◽

Detonation Waves ◽

Detonation Propagation ◽

Eddy Simulation ◽

Detonation Structure ◽

Classical Studies ◽

Large Eddy ◽

Physical Effects

Gasdynamics of detonation waves was widely studied within last hundred years - analytically, experimentally, and numerically. The majority of classical studies of the XX century were concentrated on inviscid aspects of detonation structure and propagation. There was a widespread opinion that detonation is such a fast phenomenon that viscous e¨ects should have insigni¦cant in§uence on its propagation. When the era of calculations based on the Reynolds-averaged Navier- Stokes (RANS) and large eddy simulation approaches came into effect, researchers pounced on practical problems with complex geometry and with the interaction of many physical effects. There is only a limited number of works studying the in§uence of viscosity on detonation propagation in supersonic §ows in ducts (i. e., in the presence of boundary layers).

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Numerical implementation of finite-element method of control volume using irregular mesh

Proceedings of the Mavlyutov Institute of Mechanics ◽

10.21662/uim2010.1.008 ◽

2010 ◽

Vol 7 ◽

pp. 98-108

Author(s):

Yu.A. Gafarova

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Delaunay Triangulation ◽

Complex Geometry ◽

Control Volume ◽

Test Case ◽

The Finite Element Method ◽

Irregular Mesh ◽

Discrete Analogues ◽

Element Method

To solve problems with complex geometry it is considered the possibility of application of irregular mesh and the use of various numerical methods using them. Discrete analogues of the Beltrami-Mitchell equations are obtained by the control volume method using the rectangular grid and the finite element method of control volume using the Delaunay triangulation. The efficiency of using the Delaunay triangulation, Voronoi diagrams and the finite element method of control volume in a test case is demonstrated.

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Comparison of DSMC and CFD Models of Heat Transfer in a Rarefied Two-Dimensional Geometry

Volume 7: Operations, Applications, and Components ◽

10.1115/pvp2018-84986 ◽

2018 ◽

Author(s):

Dilesh Maharjan ◽

Mustafa Hadj-Nacer ◽

Miles Greiner ◽

Stefan K. Stefanov

Keyword(s):

Heat Transfer ◽

Rarefied Gas ◽

Complex Geometry ◽

Direct Simulation Monte Carlo ◽

Accurate Method ◽

Vacuum Drying ◽

Helium Pressure ◽

Two Dimensional ◽

Dsmc Method ◽

Cfd Simulations

During vacuum drying of used nuclear fuel (UNF) canisters, helium pressure is reduced to as low as 67 Pa to promote evaporation and removal of remaining water after draining process. At such low pressure, and considering the dimensions of the system, helium is mildly rarefied, which induces a thermal-resistance temperature-jump at gas–solid interfaces that contributes to the increase of cladding temperature. It is important to maintain the temperature of the cladding below roughly 400 °C to avoid radial hydride formation, which may cause cladding embrittlement during transportation and long-term storage. Direct Simulation Monte Carlo (DSMC) method is an accurate method to predict heat transfer and temperature under rarefied condition. However, it is not convenient for complex geometry like a UNF canister. Computational Fluid Dynamics (CFD) simulations are more convenient to apply but their accuracy for rarefied condition are not well established. This work seeks to validate the use of CFD simulations to model heat transfer through rarefied gas in simple two-dimensional geometry by comparing the results to the more accurate DSMC method. The geometry consists of a circular fuel rod centered inside a square cross-section enclosure filled with rarefied helium. The validated CFD model will be used later to accurately estimate the temperature of an UNF canister subjected to vacuum drying condition.

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Sodium Metasilicate Cemented Analogue Material and Its Mechanical Properties

Advances in Materials Science and Engineering ◽

10.1155/2016/3716145 ◽

2016 ◽

Vol 2016 ◽

pp. 1-17 ◽

Cited By ~ 2

Author(s):

Songlin Yue ◽

Yanyu Qiu ◽

Pengxian Fan ◽

Pin Zhang ◽

Ning Zhang

Keyword(s):

Complex Geometry ◽

Sodium Metasilicate ◽

Raw Material ◽

Fine Aggregate ◽

Regression Equations ◽

Deformation And Failure ◽

Orthogonal Experiments ◽

Low Modulus ◽

New Type ◽

The Relationship

Analogue material with appropriate properties is of great importance to the reliability of geomechanical model test, which is one of the mostly used approaches in field of geotechnical research. In this paper, a new type of analogue material is developed, which is composed of coarse aggregate (quartz sand and/or barite sand), fine aggregate (barite powder), and cementitious material (anhydrous sodium silicate). The components of each raw material are the key influencing factors, which significantly affect the physical and mechanical parameters of analogue materials. In order to establish the relationship between parameters and factors, the material properties including density, Young’s modulus, uniaxial compressive strength, and tensile strength were investigated by a series of orthogonal experiments with hundreds of samples. By orthogonal regression analysis, the regression equations of each parameter were obtained based on experimental data, which can predict the properties of the developed analogue materials according to proportions. The experiments and applications indicate that sodium metasilicate cemented analogue material is a type of low-strength and low-modulus material with designable density, which is insensitive to humidity and temperature and satisfies mechanical scaling criteria for weak rock or soft geological materials. Moreover, the developed material can be easily cast into structures with complex geometry shapes and simulate the deformation and failure processes of prototype rocks.

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