scholarly journals NUMERICAL SIMULATIONS FOR NON CONSERVATIVE HYPERBOLIC SYSTEM. APPLICATION TO TRANSIENT TWO-PHASE FLOW WITH CAVITATION PHENOMENON

2019 ◽  
Vol 24 (2) ◽  
pp. 218-235
Author(s):  
Abdelmjid Qadi El Idrissi ◽  
Boujemâa Achchab ◽  
Abdellatif Agouzal
Keyword(s):  
Numerical Technique ◽  
Liquid Mixtures ◽  
Dissolved Gas ◽  
Two Phase ◽  
Gas Concentration ◽  
Transient Flows ◽  
Cavitation Phenomenon ◽  
The Mathematical Model ◽  
Theoretical Results ◽  
Good Agreement

A numerical method for simulating transient flows of gas-liquid mixtures is proposed. The mathematical model, established for a suspension of gas bubbles in liquid, includes an equation taking into account the relative velocity between the gas and liquid. A numerical technique based on the Mac Cormack scheme combined with the method of characteristics is presented. Theoretical results for transients initiated by a rapid closing valves are compared with measurements. A good agreement is found particularly for large values of initial dissolved gas concentration.

A NOVEL MODEL OF DIELECTRIC CONSTANT OF TWO-PHASE COMPOSITES WITH INTERFACIAL SHELLS

2002 ◽  
Vol 16 (25) ◽  
pp. 3855-3863 ◽  
Author(s):  
QINGZHONG XUE
Keyword(s):  
Dielectric Constant ◽  
Effective Dielectric Constant ◽  
Maxwell Theory ◽  
Two Phase ◽  
Random Composites ◽  
Polarization Theory ◽  
Two Phases ◽  
Novel Model ◽  
Theoretical Results ◽  
Good Agreement

Considering the interface effect between two phases in composite, we present a novel model of dielectric constant of two-phase composites with interfacial shells. Starting from Maxwell theory and average polarization theory, the formula of calculating the effective dielectric constant of two-phase random composites with interfacial shells is presented. The theoretical results on effective dielectric constant of alkyd resin paint/Barium titanate random composites with interfacial shells are in good agreement with the experimental data.

Flow of Incompressible Two-Phase Mixtures through Sharp-Edged Orifices

1967 ◽  
Vol 9 (1) ◽  
pp. 72-78 ◽  
Author(s):  
D. Chisholm
Keyword(s):  
Single Phase ◽  
Two Phase Flow ◽  
Weight Ratio ◽  
Liquid Mixtures ◽  
Theoretical Development ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Velocities ◽  
Total Mixture ◽  
Good Agreement

Equations are developed for the flow of gas-liquid or vapour-liquid mixtures through sharp-edged orifices under conditions where the density change of the gas or liquid through the orifice is negligible. The theoretical development differs from previous treatments in allowing for the interfacial shear force between the phases, and leads to an equation which is shown to be in good agreement with available experimental evidence. The determination by experiment of a single coefficient characterizing the pipe and orifice arrangement permits the prediction of both the two-phase flow rate and the ratio of the phase velocities for a given pressure drop and gas-liquid weight ratio. The range of conditions examined extends over weight ratios of gas to total mixture from 0·1 to 98 per cent, and ratios of downstream to upstream pressures greater than 0·99. The accuracy of correlation of two-phase flow data is now approaching that of single-phase flow.

Development and Validation of a Computational Code for Wet Compression Simulation of Gas Turbines

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
M. Bagnoli ◽  
M. Bianchi ◽  
F. Melino ◽  
P. R. Spina
Keyword(s):  
Gas Turbine ◽  
Process Simulation ◽  
Gas Turbines ◽  
Compression Process ◽  
Two Phase ◽  
Flow Compression ◽  
Development And Validation ◽  
Theoretical Results ◽  
Calculation Code ◽  
Good Agreement

In this paper, a calculation code, developed in house by the authors, able to evaluate the performance of a gas turbine with all possible fogging strategies (high pressure fogging, overspray, and interstage injection) is presented and discussed. The code has a flexible structure and can be applied to evaluate the performance of every commercial gas turbine model. The aim of the calculation code is to overcome the limits of the most widespread commercial software, especially with regard to the two phase flow compression process simulation. The calculation code was validated on results available in the literature showing a good agreement with experimental and theoretical results.

The Elastic Moduli of Heterogeneous Materials

1962 ◽  
Vol 29 (1) ◽  
pp. 143-150 ◽  
Author(s):  
Zvi Hashin
Keyword(s):  
Approximate Method ◽  
Elastic Moduli ◽  
Heterogeneous Materials ◽  
Theory Of Elasticity ◽  
Experimental Results ◽  
Two Phase ◽  
Concentric Spheres ◽  
Theoretical Results ◽  
Nonhomogeneous Materials ◽  
Good Agreement

Bounds and expressions for the elastic moduli of two or many phase nonhomogeneous materials are obtained by an approximate method based on the variational theorems of the theory of elasticity and on a concentric-spheres model. Theoretical results are in good agreement with experimental results for a two-phase alloy.

scholarly journals A fifth order WENO scheme for numerical simulation of shallow granular two-phase flow model

2021 ◽  
Vol 13 (9) ◽  
pp. 168781402110452
Author(s):  
Omar Rabbani ◽  
Saqib Zia ◽  
Asad Rehman
Keyword(s):  
Numerical Technique ◽  
Momentum Equation ◽  
Weno Scheme ◽  
Two Phase ◽  
Contact Discontinuities ◽  
Two Phases ◽  
Solid Liquid ◽  
Fifth Order ◽  
The Mathematical Model ◽  
Derivatives Of

In this article, a weighted essentially non-oscillatory (WENO) scheme is implemented to simulate two-phase shallow granular flow (TPSF) model. The flow is assumed to be incompressible and it is regarded as shallow layer of granular and liquid material. The mathematical model consists of two phases, that is, solid and liquid. Each phase has its continuity and momentum equation. The presence of the equations are coupled together involving the derivatives of unknowns which make it more challenging to solve. An efficient numerical technique is needed to tackle the numerical complexities. Our main intrigue is the numerical approximation of the above-mentioned solid-liquid model. The weighted essentially non-oscillatory (WENO) scheme of order 5 is utilized to handle the shock waves and contact discontinuities appear in the solution. The results are compared with the results already available in the literature by conservation element and solution element (CESE) scheme. It is observed the WENO scheme produces less errors as compared to CESE scheme and also effectively handle the shocks.

scholarly journals Numerical simulation of the formation of dry spots during film evaporation

2021 ◽  
Vol 2119 (1) ◽  
pp. 012086
Author(s):  
A V Shebelev ◽  
A V Minakov ◽  
D Y Kochkin ◽  
O A Kabov
Keyword(s):  
Numerical Technique ◽  
Calculated Data ◽  
Cell Geometry ◽  
Film Evaporation ◽  
Transfer Processes ◽  
Mass Transfer Processes ◽  
Dry Spot ◽  
The Mathematical Model ◽  
Spot Formation ◽  
Good Agreement

Abstract This paper presents a developed methodology for calculating heat and mass transfer processes in a cylindrical evaporation cell. The mathematical model reproduces all significant features of the evaporation cell geometry. In this cell, a layer of liquid is formed on a substrate with a diameter of 51 mm, heated below. To simulate heat transfer during film evaporation on a heated substrate, a numerical technique based on the Volume of Fluid method was used. The developed model was used to study the process of dry spot formation during film evaporation. The calculated data are compared with the experiment on the profile of the free surface of the film during evaporation and rupture. In general, results of this testing demonstrated good agreement with experiment. As a result, it was shown that developed numerical method makes it possible to describe process of formation dry spots.

Investigating the Nonlinear Optical Response of Pepper Oil under Low Power Irradiation with Continuous Wave Visible Laser Beam

2020 ◽  
pp. 131-138
Keyword(s):  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nonlinear Optical ◽  
Continuous Wave ◽  
Diffraction Integral ◽  
Visible Laser ◽  
Limiting Property ◽  
Kirchhoff Diffraction Integral ◽  
Theoretical Results ◽  
Good Agreement

The nonlinear optical properties of pepper oil are studied by diffraction ring patterns and Z-scan techniques with continuous wave beam from solid state laser at 473 nm wavelength. The nonlinear refractive index of the sample is calculated by both techniques. The sample show high nonlinear refractive index. Based on Fresnel-Kirchhoff diffraction integral, the far-field intensity distributions of ring patterns have been calculated. It is found that the experimental results are in good agreement with the theoretical results. Also the optical limiting property of pepper oil is reported. The results obtained in this study prove that the pepper oil has applications in nonlinear optical devices.

The study of acoustic scattering from a single sound-permeable sphere

2018 ◽  
Vol 13 (4) ◽  
pp. 79-91 ◽  
Author(s):  
E.Sh. Nasibullaeva
Keyword(s):  
Speed Of Sound ◽  
Numerical Technique ◽  
Acoustic Scattering ◽  
Computer Time ◽  
Physical Parameters ◽  
Fast Method ◽  
Scattering Field ◽  
Permeable Sphere ◽  
Test Verification ◽  
Good Agreement

The paper presents a generalized mathematical model and numerical investigation of the problem of acoustic scattering from a single sound-permeable sphere during the passage of two types of waves - spherical from a monopole radiation source and a plane one. In solving the Helmholtz equation, a numerical technique based on the fast method of multipoles is used, which allows achieving high accuracy of the results obtained at the lowest cost of computer time. The calculations are compared with known experimental data and a good agreement is obtained. The formulas for calculating the main characteristic of the scattering field (the total scattering cross section) for a sound-permeable sphere are generalized. The effect on this characteristic of the physical parameters of media outside and inside the sphere, such as the density and speed of sound, is shown. A numerical parametric analysis of the pressure distribution around a single sound-permeable sphere for different values of the wave radius, density, and speed of sound of the outer and inner medium of the sphere is carried out. The obtained results will later be used for test verification calculations for the numerical solution of the generalized problem of acoustic scattering of a set of sound-permeable spheres (coaxial or arbitrarily located in space).

Numerical modeling of the influence of bubbles on flow and heat transfer in the descending gas-liquid flow in a pipe

2012 ◽  
Vol 9 (1) ◽  
pp. 131-135
Author(s):  
M.A. Pakhomov
Keyword(s):  
Heat Transfer ◽  
Gas Phase ◽  
Liquid Flow ◽  
Bubble Diameter ◽  
Gas Content ◽  
Two Phase ◽  
Eulerian Description ◽  
Flow And Heat Transfer ◽  
Gas Liquid Flow ◽  
The Mathematical Model

The paper presents the results of modeling the dynamics of flow, friction and heat transfer in a descending gas-liquid flow in the pipe. The mathematical model is based on the use of the Eulerian description for both phases. The effect of a change in the degree of dispersion of the gas phase at the input, flow rate, initial liquid temperature and its friction and heat transfer rate in a two-phase flow. Addition of the gas phase causes an increase in heat transfer and friction on the wall, and these effects become more noticeable with increasing gas content and bubble diameter.

Numerical Modeling of Evolution of Boundary Between Incompressible Gas and Liquid in Two-Dimensional Region

2006 ◽  
Vol 4 ◽  
pp. 224-236
Author(s):  
A.S. Topolnikov
Keyword(s):  
Numerical Modeling ◽  
Interphase Boundary ◽  
Incompressible Liquid ◽  
Stokes Equations ◽  
Numerical Code ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Incompressible Media ◽  
Good Agreement

The paper is devoted to numerical modeling of Navier–Stokes equations for incompressible media in the case, when there exist gas and liquid inside the rectangular calculation region, which are separated by interphase boundary. The set of equations for incompressible liquid accounting for viscous, gravitational and surface (capillary) forces is solved by finite-difference scheme on the spaced grid, for description of interphase boundary the ideology of Level Set Method is used. By developed numerical code the set of hydrodynamic problems is solved, which describe the motion of two-phase incompressible media with interphase boundary. As a result of numerical simulation the solutions are obtained, which are in good agreement with existing analytical and experimental solutions.

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