Numerical Investigation on Wavy Streak Formation Due to Sand Erosion

2005 ◽  
Author(s):  
Masaya Suzuki ◽  
Kazuyuki Toda ◽  
Makoto Yamamoto
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Stokes Equations ◽  
Numerical Procedure ◽  
Particle Collision ◽  
Navier Stokes ◽  
Two Phase ◽  
Sand Erosion ◽  
Wall Deformation ◽  
Turbulent Flow Field

It is well known that sand erosion is a typical multi-physic problem, that is, the interactions among flow field, particle motions and wall deformation are important. To simulate this phenomenon, turbulent flow field, particle trajectories and amount of erosion on an eroded wall are calculated repeatedly. In the computations of the flow field, compressible Navier-Stokes equations and low-Reynolds-number type k-ε turbulence model are adopted. Assuming that the concentration of suspended particles is dilute, particle-particle collision and the influence of particle motions on the flow field are neglected. The Neilson-Gilchrist erosion model is used to estimate the weight loss due to erosion. Based on this numerical procedure, the gas-particle two-phase turbulent flow field in 90-degree bend with a square cross-section is simulated, in order to clarify erosion pattern formation by fluid/particle/wall interaction.

Development of Numerical Code to Predict Three-Dimensional Sand Erosion Phenomena

2003 ◽  
Author(s):  
Kuki Junichi ◽  
Kazuyuki Toda ◽  
Makoto Yamamoto
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Suspended Particle ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Numerical Code ◽  
Particle Collision ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Sand Erosion

This paper presents a numerical procedure to predict a three-dimensional sand erosion phenomenon and the interaction between the flow field and the eroded surface. To simulate this phenomenon, the turbulent flow field, the particle trajectory and the amount of erosion on the eroded wall are calculated repeatedly. In computations of the flow field, compressible Navier-Stokes equations and low-Reynolds-number type k–ε turbulence model are adopted. Assuming that the concentration of suspended particle is dilute, particle-particle collision and the influence of particle motions on the flow field are neglected. The Neilson-Gilchrist erosion model is used to estimate the weight loss due to erosion. To verify the developed code, two types of 90-degree bends are computed. The results show that the present procedure can reasonably reproduce the sand erosion process and the temporal change of both the flow field and the wall surface qualitatively.

Numerical Simulation of Sand Erosion Phenomena in Square-Section 90 Degree Bend With Linear/Nonlinear RANS Turbulence Models

2007 ◽  
Author(s):  
Masaya Suzuki ◽  
Kazuaki Inaba ◽  
Makoto Yamamoto
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Turbulence Models ◽  
Solid Particles ◽  
Two Phase ◽  
Streamline Curvature ◽  
Sand Erosion ◽  
Rans Turbulence Models ◽  
Wall Deformation ◽  
Bend Flow

Sand erosion is a phenomenon where solid particles impinging to a wall cause serious mechanical damages to the wall surface. This phenomenon is a typical gas-particle two-phase turbulent flow and a multi-physics problem where the flow field, particle trajectory and wall deformation interact with among others. On the other hand, the sand erosion is a serious problem to install pneumatic conveying systems for handling abrasive materials. Incidentally, the bend erosion is typical target of sand erosion experiments and is useful for verification of numerical simulations. Although, the secondary flow which occurs in such a flow field including streamline curvature cannot be reproduced by the standard k-ε model. To predict this flow field, a more universal model which can estimate anisotropic Reynolds stress is required. In the present study, we simulate sand erosion of 90 degree bend with a square cross-section. We use some linear/nonlinear turbulence models to predict the secondary flow of the bend. Besides, the performance of each model to predict clear/eroded bend flow field is studied.

scholarly journals Dynamic Measurements with the Bicone Interfacial Shear Rheometer: Numerical Bench-Marking of Flow Field Based Data Processing

2018 ◽  
Author(s):  
Pablo Sánchez-Puga ◽  
Javier Tajuelo Rodríguez ◽  
Juan Manuel Pastor ◽  
Miguel Ángel Rubio
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Amplitude Ratio ◽  
Numerical Procedure ◽  
Complex Viscosity ◽  
Detailed Comparison ◽  
Interfacial Shear ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Air Water Interface

Flow field based methods are becoming increasingly popular for the analysis of interfacial shear rheology data. Such methods take properly into account the subphase drag by solving the Navier-Stokes equations for the bulk phases flows, together with the Boussinesq-Scriven boundary condition at the fluid-fluid interface, and the probe equation of motion. Such methods have been successfully implemented at the double wall-ring (DWR), the magnetic rod (MR), and the bicone interfacial shear rheometers. However, a study of the errors introduced directly by the numerical processing is still lacking. Here we report on a study of the errors introduced exclusively by the numerical procedure corresponding to the bicone geometry at an air-water interface. In our study we directly input a preset the value of the complex interfacial viscosity and we numerically obtain the corresponding flow field and the complex amplitude ratio for the probe motion. Then we use the standard iterative procedure to obtain the calculated complex viscosity value. A detailed comparison of the set and calculated complex viscosity values is made upon changing different parameters such as real and imaginary parts of the complex interfacial viscosity and frequency. The observed discrepancies yield a detailed landscape of the numerically introduced errors.

Implementation and Development of a Stochastic Turbulence Model Based on RANS Formulation for the Prediction of Aeroacoustic Noise

2005 ◽  
Author(s):  
Phachara Niumsawatt ◽  
Sylvester Abanteriba
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Isotropic Turbulence ◽  
Sound Propagation ◽  
Stokes Equations ◽  
Low Cost ◽  
Attractive Alternative ◽  
Generation Model ◽  
Aeroacoustic Noise ◽  
Turbulent Flow Field

In the computation of aeroacoustic noise, both the Lighthill analogy and the linearized Euler approaches require the definition of source terms involving instantaneous flow fluctuations, which are generally obtained from either Direct Numerical Simulation (DNS) or Large Eddy Simulation (LES). However, these approaches are not economically viable in terms of computational resources, as they require very fine grids to deliver accurate results. Therefore, the Stochastic Velocity Field generation model (SVFG) has has been applied in this paper. The SVFG model is based on the concept of the Stochastic Noise Generation and Radiation (SNGR) without sound propagation and linearized equations. The SVFG model uses time-averaged quantities from the Reynolds Averaged Navier-Stokes equations (RANS) to generate a synthetic time dependent turbulent flow field. The turbulent fluctuations are modeled using a stochastic description of the three-dimensional turbulent motion with a discrete set of Fourier modes. This synthetic turbulent field represents many of the characteristics of real turbulence. Nevertheless, it still has some imperfections; although it exhibits the expected correlation length and the required ratio of length scales, it does not predict the convective properties of shear flow turbulence, as the approach generates homogenous and isotropic turbulence. These properties are shown in this paper with the test case of an axial-symmetrical subsonic jet. The SVFG model is used to generate the turbulent flow field, which then is used to compare with actual experiment measurement and other prediction methods. The results of the comparison show strengths and weaknesses of the model. Since the SVFG approach is relatively low cost when compared to both LES and DNS, it offers an attractive alternative to derive the turbulent flow field.

Numerical Turbulent Analysis for Flow Around a Square Cylinder Using the Finite Element Method

2003 ◽  
Author(s):  
Shinichiro Miura ◽  
Kazuhiko Kakuda
Keyword(s):  
Finite Element ◽  
Flow Field ◽  
Turbulent Flow ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Square Cylinder ◽  
Weak Formulation ◽  
Finite Element Scheme ◽  
Navier Stokes Equations ◽  
Element Scheme

A finite element scheme based on the Petrov-Galerkin weak formulation using exponential weighting functions for solving accurately, and in a stable manner, the flow field of an incompressible viscous fluid has been proposed in our previous works. In this paper, we present the Petrov-Galerkin finite element scheme for turbulent flow field. The incompressible Navier-Stokes equations are numerically integrated in time by using a fractional step strategy with second-order accurate Adams-Bashforth explicit differencing for both convection and diffusion terms. Numerical results obtained herein are compared through turbulent flow around a square cylinder at Re = 22,000 with the experimental data and other existing numerical ones.

Computational Analysis of Two-Phase Mixing Inside a Twin-Fluid, Fuel-Flexible Atomizer

2017 ◽  
Author(s):  
Nathan J. Vardaman ◽  
Ajay K. Agrawal
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Fuel Injector ◽  
Cfd Model ◽  
Two Phase ◽  
Phase Mixing ◽  
Phase Mixture

We have developed a twin-fluid atomizer for combustion that creates a two-phase mixture of fuel and atomizing air upstream of the injector exit where a high-pressure region is established. The static pressure decreases rapidly as the fuel-air mixture exits from the injector, which causes air bubbles in the mixture to expand and breakup the surrounding liquid. This type of fuel injector can effectively atomize various biofuels including highly viscous straight vegetable oil and glycerol. While the combustion benefits have been demonstrated in our prior studies, an understanding of the underlying flow field and mechanism of the two-phase mixture formation process within the injector remains elusive. In this study, a computational fluid dynamic (CFD) model is developed to investigate the two-phase mixing and how it is affected by the operating conditions, particularly the atomizing air to liquid ratio (ALR) by mass. The axisymmetric isothermal CFD model, based on the mixture model for two-phase flows and Reynolds averaged Navier-Stokes equations, utilizes air and water as the working fluids. Both fluids are treated as incompressible, with constant fluid properties. The analysis reveals the flow field within the injector and successfully replicates the upstream penetration of the atomizing air into the liquid supply tube observed experimentally. The penetration depth increases with increase in the ALR, which again agrees with the experimental results.

scholarly journals Dynamic Measurements with the Bicone Interfacial Shear Rheometer: Numerical Bench-Marking of Flow Field-Based Data Processing

2018 ◽  
Vol 2 (4) ◽  
pp. 69 ◽  
Author(s):  
Pablo Sánchez-Puga ◽  
Javier Tajuelo ◽  
Juan Pastor ◽  
Miguel Rubio
Keyword(s):  
Flow Field ◽  
Stokes Equations ◽  
Amplitude Ratio ◽  
Numerical Procedure ◽  
Complex Viscosity ◽  
Detailed Comparison ◽  
Interfacial Shear ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Made In

Flow field-based methods are becoming increasingly popular for the analysis of interfacial shear rheology data. Such methods take properly into account the subphase drag by solving the Navier–Stokes equations for the bulk phase flows, together with the Boussinesq–Scriven boundary condition at the fluid–fluid interface and the probe equation of motion. Such methods have been successfully implemented on the double wall-ring (DWR), the magnetic rod (MR), and the bicone interfacial shear rheometers. However, a study of the errors introduced directly by the numerical processing is still lacking. Here, we report on a study of the errors introduced exclusively by the numerical procedure corresponding to the bicone geometry at an air–water interface. In our study, we set an input value of the complex interfacial viscosity, and we numerically obtained the corresponding flow field and the complex amplitude ratio for the probe motion. Then, we used the standard iterative procedure to obtain the calculated complex viscosity value. A detailed comparison of the set and calculated complex viscosity values was made in wide ranges of the three parameters herein used, namely the real and imaginary parts of the complex interfacial viscosity and the frequency. The observed discrepancies yield a detailed landscape of the numerically-introduced errors.

Comparative Study of RANS and LES Simulation Methods for Analysis of Turbulence in a Tubular Stirred Reactor

2012 ◽  
Vol 499 ◽  
pp. 218-222 ◽  
Author(s):  
Qiu Yue Zhao ◽  
Ting An Zhang ◽  
Yan Liu ◽  
Xiao Chang Cao ◽  
Shu Chan Wang ◽  
...  
Keyword(s):  
Standard Model ◽  
Flow Field ◽  
Turbulent Flow ◽  
Mixing Time ◽  
Simulation Method ◽  
Navier Stokes ◽  
Stirred Reactor ◽  
Large Eddy ◽  
Turbulent Flow Field ◽  
Better Than

Selecting a right simulation method is important for accurately predicting flow field in stirred reactor. The Reynolds-Averaged Navier-Stokes (RANS) approach with standard model and large eddy simulations (LES) method were both used to analyze the turbulent flow field in a tubular stirred reactor for leaching. Calculations were performed to study the effects of agitator speed and flux on the turbulent flow field. The velocity at different axial sections gained by the two methods was compared. Results showed that the eddy current, especially in the back of impellor, predicted by LES was better than that by standard model. At the same time，the average relative error of the mean residence time and the mixing time of the former reduced 5% and 13% respectively than that of the latter.

MATHEMATICAL MODELING OF A TURBULENT FLOW IN A CENTRIFUGAL SEPARATOR

2021 ◽  
pp. 121-138
Author(s):  
Z.M. Malikov ◽  
◽  
M.E. Madaliev ◽  
Keyword(s):  
Mathematical Modeling ◽  
Turbulent Flow ◽  
Gas Flow ◽  
Stokes Equations ◽  
Solid Phase ◽  
Navier Stokes ◽  
Centrifugal Separator ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Carrier Gas Flow

The numerical results of mathematical modeling of a two-phase axisymmetric swirling turbulent flow in a separation zone of a centrifugal separator are presented. The motion of the carrier gas flow is described by the Reynolds-averaged Navier-Stokes equations. A system of equations is enclosed by the Spalart-Allmaras turbulence model. The study is based on the obtained fields of averaged velocities of the carrier medium, with account for turbulent diffusion. Numerical solution to the problem is implemented using the semi-implicit method for pressure linked equations (SIMPLE). The results obtained when the solid phase effect on the air flow dynamics is taken into account are compared with those obtained when the effect is left out of account. The numerical calculations are validated using the experimental data.

Numerical Simulation of Sand Erosion Phenomena in Rotor/Stator Interaction of Compressor

2006 ◽  
Author(s):  
Masaya Suzuki ◽  
Kazuaki Inaba ◽  
Makoto Yamamoto
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Flow ◽  
Solid Particles ◽  
Aircraft Engines ◽  
Two Phase ◽  
Erosion Prediction ◽  
Sand Erosion ◽  
Wall Deformation ◽  
Rotor Stator Interaction

Sand erosion is a phenomenon where solid particles impinging to a wall cause serious mechanical damages to the wall surface. This phenomenon is a typical gas-particle two-phase turbulent flow and a multi-physics problem where the flow field, particle trajectory and wall deformation interact with among others. On the other hand, aircraft engines operating in a particulate environment are subjected to the performance and lifetime deterioration due to sand erosion. Especially, the compressor of the aircraft engines is severely damaged. The flow fields of the compressor have strongly three dimensional and unsteady characters. In order to estimate the deterioration due to sand erosion, the sand erosion simulation for the compressor is required under the consideration of the rotor-stator interaction. In the present study, we apply our three dimensional sand erosion prediction code to a single stage axial flow compressor. We numerically investigate the change of the flow field, the particle trajectories, and the eroded wall shape in the compressor, to clarify the effects of sand erosion.

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