scholarly journals A global analysis of the atmospheric pollutant modeling

2007 ◽  
Vol 22 (1) ◽  
pp. 1-9
Author(s):  
Umberto Rizza ◽  
Jonas C. Carvalho ◽  
Davidson M. Moreira ◽  
Marcelo R. Moraes ◽  
Antônio G. Goulart
Keyword(s):  
Global Analysis ◽  
Turbulent Transport ◽  
Three Dimensional ◽  
Ground Level ◽  
Lagrangian Model ◽  
Linear Superposition ◽  
Atmospheric Pollutant ◽  
Advection Diffusion Equation ◽  
Laplace Transform Technique ◽  
The Laplace Transform

In this article is carried out a comparison between Lagrangian and Eulerian modelling of the turbulent transport of pollutants within the Planetary Boundary Layer (PBL). The Lagrangian model is based on a three-dimensional form of the Langevin equation for the random velocity. The Eulerian analytical model is based on a discretization of the PBL in N sub-layers; in each of the sub-layers the advection-diffusion equation is solved by the Laplace transform technique. In the Eulerian numerical model the advective terms are solved using the cubic spline method while a Crank-Nicholson scheme is used for the diffusive terms. The models use a turbulence parameterization that considers a spectrum model, which is given by a linear superposition of the buoyancy and mechanical effects. Observed ground-level concentrations measured in a dispersion field experiment are used to evaluate the simulations.

scholarly journals Evaluation of two semi-analytical techniques in air quality applications

2007 ◽  
Vol 22 (1) ◽  
pp. 10-20
Author(s):  
Jonas C. Carvalho ◽  
Davidson M. Moreira
Keyword(s):  
Analytical Techniques ◽  
Ground Level ◽  
Lagrangian Model ◽  
Computational Time ◽  
Eulerian Model ◽  
Model Based ◽  
Advection Diffusion Equation ◽  
Ground Level Concentration ◽  
Laplace Transform Technique ◽  
The Laplace Transform

In this article an evaluation of two semi-analytical techniques is carried out, considering the quality and accuracy of these techniques in reproducing the ground-level concentration values of passive pollutant released from low and high sources. The first technique is an Eulerian model based on the solution of the advection-diffusion equation by the Laplace transform technique. The second is a Lagrangian model based on solution of the Langevin equation through the Picard Iterative Method. Turbulence parameters are calculated according to a parameterization capable of generating continuous values in all stability conditions and in all heights of the planetary boundary layer. Numerical simulations and comparisons show a good agreement between predicted and observed concentrations values. Comparisons between the two proposed techniques reveal that Lagrangian model generated more accurate results, but Eulerian model demands a lesser computational time.

scholarly journals Convergence of the uniaxial PML method for time-domain electromagnetic scattering problems

2021 ◽  
Author(s):  
Changkun Wei ◽  
Jiaqing Yang ◽  
Bo Zhang
Keyword(s):  
Time Domain ◽  
Electromagnetic Scattering ◽  
Scattering Problem ◽  
Three Dimensional ◽  
Scattering Problems ◽  
Laplace Transform Technique ◽  
The Laplace Transform ◽  
Time Domain Electromagnetic ◽  
Numer Anal ◽  
The Time Domain

In this paper, we propose and study the uniaxial perfectly matched layer (PML) method for three-dimensional time-domain electromagnetic scattering problems, which has a great advantage over the spherical one in dealing with problems involving anisotropic scatterers. The truncated uniaxial PML problem is proved to be well-posed and stable, based on the Laplace transform technique and the energy method. Moreover, the $L^2$-norm and $L^{\infty}$-norm error estimates in time are given between the solutions of the original scattering problem and the truncated PML problem, leading to the exponential convergence of the time-domain uniaxial PML method in terms of the thickness and absorbing parameters of the PML layer. The proof depends on the error analysis between the EtM operators for the original scattering problem and the truncated PML problem, which is different from our previous work (SIAM J. Numer. Anal. 58(3) (2020), 1918-1940).

scholarly journals A New Direction in the Atmospheric Pollutant Dispersion inside the Planetary Boundary Layer

2018 ◽  
Vol 57 (1) ◽  
pp. 185-192 ◽  
Author(s):  
Davidson Moreira ◽  
Marcelo Moret
Keyword(s):  
Boundary Layer ◽  
Fractional Derivative ◽  
Planetary Boundary Layer ◽  
Atmospheric Dispersion ◽  
Gaussian Model ◽  
Pollutant Dispersion ◽  
Atmospheric Pollutant ◽  
Advection Diffusion Equation ◽  
Laplace Transform Technique ◽  
Better Than

AbstractIn this study, an analytical solution for the steady-state fractional advection–diffusion equation was obtained to simulate the atmospheric dispersion of pollutants in a vertically inhomogeneous planetary boundary layer. The authors propose a method that uses the modified generalized integral Laplace transform technique to solve the transformed problem with a fractional derivative, resulting in a more general solution. The model results were compared with the fractional Gaussian model and demonstrate that, when considering an experimental dataset under moderately unstable conditions, fractional-derivative models perform better than traditional integer-order models.

scholarly journals Modelo de pluma segmento com velocidades estocásticas para dispersão atmosférica em condições de vento fraco

2020 ◽  
Vol 42 ◽  
pp. e11
Author(s):  
Camila Fávero ◽  
Glênio Aguiar Gonçalves ◽  
Daniela Buske ◽  
Régis Sperotto de Quadros ◽  
Viliam Cardoso da Silveira
Keyword(s):  
Computational Cost ◽  
Three Dimensional ◽  
Pollutant Dispersion ◽  
Wind Condition ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Laplace Transform Technique ◽  
Integral Laplace Transform ◽  
Variable Separation Method ◽  
Temporal Variable

This work presents an analytical solution for the transient three-dimensional advection-diffusion equation. This solution, obtained from a combination of the variable separation method and GILTT (Generalized Integral Laplace Transform Technique) is used to simulate the pollutant dispersion in the atmosphere. The new solution has the advantage of not requiring a numerical inversion performed in the temporal variable in works using only GILTT technique. The model was tested in low wind condition, with diffusion in transverse and longitudinal directions and stochastic speeds. Simulations were performed for the INEL experiment. The analytical character of the model makes it simple, which represents advantages in its development and implementation, as well as in the computational cost for execution.

Unsteady three-dimensional sources in deep water with an elastic cover and their applications

2013 ◽  
Vol 730 ◽  
pp. 392-418 ◽  
Author(s):  
Izolda V. Sturova
Keyword(s):  
Three Dimensional ◽  
Initial Boundary ◽  
Initial Boundary Value Problem ◽  
Uniform Density ◽  
Forward Speed ◽  
Submerged Sphere ◽  
Laplace Transform Technique ◽  
The Laplace Transform ◽  
Long Time ◽  
Initial Boundary Value

AbstractThe velocity potential is derived for a transient source of arbitrary strength undergoing arbitrary three-dimensional motion. The initially quiescent fluid of infinite depth is assumed to be inviscid, incompressible and homogeneous. The upper surface of the fluid is covered by a thin layer of elastic material of uniform density with lateral stress. The linearized initial boundary-value problem is formulated within the framework of the potential-flow theory, and the Laplace transform technique is employed to obtain the solution. The potential of a time-harmonic source with forward speed is obtained as a particular case. The far-field wave motion at long time is determined via the method of stationary phase. The problems of radiation (surge, sway and heave) of the flexural–gravity waves by a submerged sphere advancing at constant forward speed are investigated. The method of multipole expansions is used. Numerical results are obtained for the wave-making resistance and lift, added-mass and damping coefficients. The effects of an ice sheet and broken ice on the hydrodynamic loads are discussed in detail.

Mixed- and crack-type dynamical problems of electro-magneto-elasticity theory

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Tengiz Buchukuri ◽  
Otar Chkadua ◽  
David Natroshvili
Keyword(s):  
Elasticity Theory ◽  
Existence And Uniqueness ◽  
Mixed Boundary ◽  
Asymptotic Properties ◽  
Three Dimensional ◽  
Potential Method ◽  
Laplace Transform Technique ◽  
Crack Type ◽  
The Laplace Transform ◽  
Anisotropic Bodies

AbstractWe investigate the solvability of three-dimensional dynamical mixed boundary value problems of electro-magneto-elasticity theory for homogeneous anisotropic bodies with interior cracks. Using the Laplace transform technique, the potential method, and the theory of pseudodifferential equations, we prove the existence and uniqueness theorems and analyze asymptotic properties of solutions near the crack edges and near the lines where the different boundary conditions collide.

scholarly journals Simulation of three-dimensional transient pollutant dispersion in low wind conditions using the 3D-GILTT technique

2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Viliam Cardoso Da Silveira ◽  
Daniela Buske ◽  
Régis Sperotto De Quadros
Keyword(s):  
Diffusion Equation ◽  
Integral Transform ◽  
Dispersion Model ◽  
Three Dimensional ◽  
Pollutant Dispersion ◽  
Transient Model ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Laplace Transform Technique ◽  
The Usa

The aim of this work is to present a transient model in low wind conditionsto simulate the pollutants dispersion in the atmosphere. The dispersion model is based in the advection-diffusion equation and it considers the zonal and meridional components of the wind. The transient advection-diffusion equation is solved using integral transform techniques. In this work, the generalized integral transform and Laplace techniques are used, known in the literature as GILTT and which applied to the three-dimensional problem is called 3D-GILTT (Three-dimensional Generalized Integral Laplace Transform Technique). To validate the model, data from INEL experiment (Idaho National Engineering Laboratory) carried out in the USA were used. The model simulates the observed concentrations in a satisfactory way and can be used for regulatory air quality applications

Study on the generalized k-Hilfer–Prabhakar fractional viscoelastic–plastic model

2021 ◽  
pp. 108128652110258
Author(s):  
Yi-Ying Feng ◽  
Xiao-Jun Yang ◽  
Jian-Gen Liu ◽  
Zhan-Qing Chen
Keyword(s):  
Constitutive Model ◽  
Three Dimensional ◽  
Sensitivity Analyses ◽  
Creep Process ◽  
Fractional Operator ◽  
Modified Model ◽  
Proposed Model ◽  
Accelerated Creep ◽  
The Laplace Transform ◽  
Classical Models

The general fractional operator shows its great predominance in the construction of constitutive model owing to its agility in choosing the embedded parameters. A generalized fractional viscoelastic–plastic constitutive model with the sense of the k-Hilfer–Prabhakar ( k-H-P) fractional operator, which has the character recovering the known classical models from the proposed model, is established in this article. In order to describe the damage in the creep process, a time-varying elastic element [Formula: see text] is used in the proposed model with better representation of accelerated creep stage. According to the theory of the kinematics of deformation and the Laplace transform, the creep constitutive equation and the strain of the modified model are established and obtained. The validity and rationality of the proposed model are identified by fitting with the experimental data. Finally, the influences of the fractional derivative order [Formula: see text] and parameter k on the creep process are investigated through the sensitivity analyses with two- and three-dimensional plots.

scholarly journals Simulation of denitrification and ozone loss for the Arctic winter 2002/2003

2005 ◽  
Vol 5 (6) ◽  
pp. 1437-1448 ◽  
Author(s):  
J.-U. Grooß ◽  
G. Günther ◽  
R. Müller ◽  
P. Konopka ◽  
S. Bausch ◽  
...  
Keyword(s):  
Inorganic Nitrogen ◽  
Potential Temperature ◽  
Three Dimensional ◽  
Lagrangian Model ◽  
The Arctic ◽  
Particle Nucleation ◽  
Ozone Loss ◽  
Dimensional Version ◽  
Total Inorganic Nitrogen ◽  
Catalytic Cycles

Abstract. We present simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) for the Arctic winter 2002/2003. We integrated a Lagrangian denitrification scheme into the three-dimensional version of CLaMS that calculates the growth and sedimentation of nitric acid trihydrate (NAT) particles along individual particle trajectories. From those, we derive the HNO3 downward flux resulting from different particle nucleation assumptions. The simulation results show a clear vertical redistribution of total inorganic nitrogen ( ), with a maximum vortex average permanent removal of over 5ppb in late December between 500 and 550K and a corresponding increase of of over 2ppb below about 450K. The simulated vertical redistribution of is compared with balloon observations by MkIV and in-situ observations from the high altitude aircraft Geophysica. Assuming a globally uniform NAT particle nucleation rate of 7.8x10-6cm-3h-1 in the model, the observed denitrification is well reproduced. In the investigated winter 2002/2003, the denitrification has only moderate impact (≤14%) on the simulated vortex average ozone loss of about 1.1ppm near the 460K level. At higher altitudes, above 600K potential temperature, the simulations show significant ozone depletion through -catalytic cycles due to the unusual early exposure of vortex air to sunlight.

Sign in / Sign up

Export Citation Format

Share Document