scholarly journals Simulation of Aerosol Evolution within Background Pollution for Nucleated Vehicle Exhaust via TEMOM

2021 ◽  
Vol 11 (10) ◽  
pp. 4552
Author(s):  
Can Tu ◽  
Yueyan Liu ◽  
Taiquan Wu ◽  
Mingzhou Yu
Keyword(s):  
Taylor Series Expansion ◽  
Expansion Method ◽  
Navier Stokes ◽  
Vehicle Exhaust ◽  
Navier Stokes Equation ◽  
Brownian Coagulation ◽  
Background Pollution ◽  
Measurement Results ◽  
The Relationship ◽  
Parameterization Model

This work is intended to study the effect of background particles on vehicle emissions in representative realistic atmospheric environments. The coupling of Reynolds-Averaged Navier–Stokes equation (RANS) and Taylor-series Expansion Method Of Moments (TEMOM) is performed to track the emissions of the vehicle and simulating the evolution of the matters. The transport equation of mass, momentum, heat, and the first three orders of moments are taken into account with the effect of binary homogeneous nucleation, Brownian coagulation, condensation, and thermophoresis. The parameterization model is utilized for nucleation. The measured data for Beijing’s particle size distribution under both polluted and nonpolluted conditions are utilized as background particles. The relationship between the macroscopic measurement results and the microscopic dynamic process is analyzed by comparing the variation trend of several physical quantities in the process of aerosol evolution. It is found with an increase of background particle concentration, the nucleation is inhibited, which is consistent with the existing studies.

scholarly journals The Fundamental Aspects of TEMOM Model for Particle Coagulation due to Brownian Motion—Part II: In the Continuum Regime

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
He Qing ◽  
Xie Mingliang
Keyword(s):  
Taylor Series Expansion ◽  
Expansion Method ◽  
Order Moment ◽  
Method Of Moment ◽  
Brownian Coagulation ◽  
Theoretical System ◽  
The Relationship ◽  
Expansion Point ◽  
The Continuum ◽  
Series Expansion Method

The fundamental aspects of the Taylor-series expansion method of moment (TEMOM) model proposed to model the aerosol population balance equation due to Brownian coagulation in the continuum regime is shown in this study, such as the choice of the expansion pointu, the relationship between asymptotic behavior and analytical solution, and the error of the high-order moment equations. All these analyses will contribute to the buildup of the theoretical system of the TEMOM model.

NUMERICAL SIMULATION FOR NUCLEATED VEHICLE EXHAUST PARTICULATE MATTERS VIA THE TEMOM/LES METHOD

2009 ◽  
Vol 20 (03) ◽  
pp. 399-421 ◽  
Author(s):  
MINGZHOU YU ◽  
JIANZHONG LIN ◽  
TATLEUNG CHAN
Keyword(s):  
Sulfur Content ◽  
Particle Diameter ◽  
Taylor Series Expansion ◽  
Expansion Method ◽  
Computational Time ◽  
Geometric Standard Deviation ◽  
Particulate Matters ◽  
Vehicle Exhaust ◽  
Brownian Coagulation ◽  
Environment Temperature

The combination of large eddy simulation (LES) and newly proposed Taylor-series expansion method of moments (TEMOM) is performed for simulating particulate matters emitted from vehicle engine tailpipe. The momentum, heat and mass transfer, binary homogeneous nucleation, Brownian coagulation, Brownian and turbulent diffusion, condensation and thermophoresis are simultaneously taken into account. Good agreements between the experimental and simulated results with respect to the pollutant dispersion are obtained. Compared to other published methods, the present TEMOM requires the least computational time with much accuracy for predicting nanoparticle dynamics. The instantaneous results show that large eddies dominate the evolution of particulate dynamics as exhaust develops, while binary homogeneous sulfuric-water nucleation mainly appears at the interface between the exhaust and ambient cool gases. The increasing of fuel sulfur content and relative humidity or the decreasing of environment temperature leads to an increase in particulate product rate, while volume-averaged particle diameter increases with increasing fuel sulfur content and environment temperature. The variation of geometric standard deviation suggests the nucleated particles eventually approach the asymptotic distribution in the dilution atmosphere, and this distribution is independent of the fuel sulfur content. The variance of upstream turbulence intensity significantly affects the evolution of particulate matters inside the plume.

scholarly journals High concentration Brownian coagulation in jet flow using two enhancement formulations

2012 ◽  
Vol 16 (5) ◽  
pp. 1519-1523
Author(s):  
Pei-Feng Lin ◽  
Di-Chong Wu ◽  
Ze-Fei Zhu
Keyword(s):  
Volume Fraction ◽  
Taylor Series Expansion ◽  
Expansion Method ◽  
High Volume ◽  
Jet Flow ◽  
High Concentration ◽  
Brownian Coagulation ◽  
Planar Jet ◽  
Ultra Fine Particle ◽  
The One

Ultra-fine particle coagulation by Brownian motion at high concentration in planar jet flow is simulated. A Taylor-Series Expansion Method of Moments is employed to solve the particle general dynamic equation. The volume fraction gets high value, very closes to that at the nozzle exit. As the vortex pairing develops, the high volume fraction region rolls out and mixes with the low value region. The enhancement factor given by Trzeciak et al. will be less than one at some specific outer positions, which seems to be less accurate than the one given by Heine et al.

scholarly journals Mathematical modelling of fluid flow in electromagnetically stirred weld pool

2021 ◽  
Vol 1201 (1) ◽  
pp. 012025
Author(s):  
K Enger ◽  
M G Mousavi ◽  
A Safari
Keyword(s):  
Fluid Flow ◽  
Grain Refinement ◽  
Weld Pool ◽  
Fluid Velocity ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Turbulent Fluid Flow ◽  
Flow Modelling ◽  
Weld Parameters ◽  
The Relationship

Abstract In this paper, a mathematical model has been proposed to study the relationship between electromagnetic stirring (EMS) weld parameters and the mode of fluid flow on grain refinement of AA 6060 weldments. For this purpose, fluid flow modelling using Navier-Stokes equation is described first, and then, the proposed mathematical approach has been discussed in detail. For demonstration, calculations to determine the fluid velocity in the weld pool of thin plate AA6060 were performed. The application of the model on the experimental results indicates that the best grain refinement is achieved at a transition mode from laminar to turbulent fluid flow.

The virtual power principle in fluid mechanics

2014 ◽  
Vol 744 ◽  
pp. 310-328 ◽  
Author(s):  
Yongliang Yu
Keyword(s):  
Incompressible Flows ◽  
Boundary Energy ◽  
Fluid Motion ◽  
Navier Stokes ◽  
Analytical Mechanics ◽  
Virtual Power ◽  
Navier Stokes Equation ◽  
Fluid Medium ◽  
External Forces ◽  
The Relationship

AbstractA conceptual framework on analytical mechanics for continuous fluid medium, which connects the fluid motion and all of the (internal and external) forces with mechanical power, is proposed by using the virtual power and the virtual velocity. Based on this framework, it is found that the internal virtual power is equal to the external virtual power in fluid dynamics, which is called the virtual power principle. This framework is also proved to be equivalent to the vector dynamics (Cauchy’s equation or Navier–Stokes equation). Furthermore, based on the virtual power principle, a theorem is introduced for continuous fluid medium, which indicates the relationship between the force (or torque) acting on a body immersed in a fluid and the specified virtual power. Subsequently, according to Galilean invariance, the detailed relationship for Newtonian fluids in incompressible flows is derived and used to illustrate the mechanisms on instantaneous forces: the added inertial effects, the boundary energy flux and dissipation effects, the vortex contribution, and the explicit body force contribution. As an application of the principle, the advantage of the V formation flight of geese is preliminarily discussed in the view of aerodynamics. Specifically, the total drag of the flock is reduced by contrast with the simple sum of the drag in solo fight and the optimal angle of V ranges from $60^{\circ }$ to $120^{\circ }$. The principle could be a useful approach to reveal the contributions of the flow structures and the moving or deforming boundaries to the force and torque acting on a body, especially in a multibody system.

Unsteady Flow Numerical Simulation in a Double Channel Pump and Measurements of Pressure Fluctuation at Volute Outlet

2009 ◽  
Author(s):  
Hou-lin Liu ◽  
Ming-zhen Lu ◽  
Bin-bin Lu ◽  
Ming-gao Tan ◽  
Yong Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Sliding Mesh ◽  
Measurement Results ◽  
Double Channel ◽  
Fft Analysis

Adopting the Reynolds averaged Navier-Stokes equation and RNG k-ε turbulent model, the unsteady flow in the double channel pump is simulated with sliding mesh technique. Detecting points in the impeller and volute passages are to capture the pressure fluctuation law at different time. The pressure fluctuation around the outlet of the volute is measured by pressure transducer, then the frequency domain pattern under different conditions comes out. With the Fast Fourier transform (FFT) analysis, the pressure changing law of time domain at the outlet of the volute is investigated under different operating conditions. It shows that the pressure fluctuation in the volute differs under different conditions. The pressure changing law obtained by the numerical simulation at the outlet of the volute accords with the measurement results. Also the pressure fluctuation at the outlet of the volute is closely related to the interaction between impeller and volute.

The Influence of the Number of Impeller’s Blade on the Performance of Multistage Centrifugal Pump

2013 ◽  
Vol 781-784 ◽  
pp. 2851-2856
Author(s):  
Ling Yi ◽  
Zhi Peng Li ◽  
Yan Hui Chen ◽  
Shun Jun Hong
Keyword(s):  
Numerical Simulation ◽  
Comparative Analysis ◽  
Flow Characteristics ◽  
Internal Flow ◽  
The Self ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Blade Number ◽  
Multistage Centrifugal Pump ◽  
The Relationship

Abstract: In order to understand the relationship between the number of blade and the performance of the self-balance multistage centrifugal pump’s first stage impeller internal flow characteristics, Reynolds Navier-Stokes equation and κ~ε turbulence model are used for numerical simulation. The objects of numerical simulation are five self-balance multistage centrifugal pump’s first stage impellers, the blade number of them is 4，5，6，7，8.Under the rated flow ,the numerical simulation obtain five kind of impeller inner flow field distribution , Through the comparative analysis ,when the number of blade is 4,8,the flow of the impeller’s inner and pressure distribution become chaos ;And, the number of blade is 5,6,7, With the increase of blade number, the impeller internal flow are smoother，the head and efficiency are enhanced correspondingly.

Numerical Study of Cavitation on Hydrofoils

2010 ◽  
Vol 44-47 ◽  
pp. 2001-2005
Author(s):  
Jing Hu ◽  
Xian Zhou Wang ◽  
Ming Yue Liu ◽  
Zhi Guo Zhang ◽  
Qi Zhou
Keyword(s):  
Numerical Simulation ◽  
Stokes Equation ◽  
Turbulence Model ◽  
Volume Fraction ◽  
Numerical Study ◽  
Navier Stokes ◽  
Special Focus ◽  
Navier Stokes Equation ◽  
The Relationship ◽  
Incompressible Navier Stokes Equation

Based on CFD technology, flow around a 2-dimentional hydrofoil of highly skewed propeller and NACA series hydrofoils are simulated using 2D incompressible Navier-Stokes equation with Realizable k- turbulence model. In the numerical simulation, the vapor volume fraction is calculated for different cavitation numbers and angles of attack by adding the mixture model. The hydrofoil’s performance and the relationship with hydrofoil parameter are qualitatively analyzed. Special focus is given to the influence of the cavitation numbers and angle of attack on cavitation characteristics.

Sign in / Sign up

Export Citation Format

Share Document