The Experts below are selected from a list of 147 Experts worldwide ranked by ideXlab platform

Ana Graciela Ulke - One of the best experts on this subject based on the ideXlab platform.

  • assessment of the unified analytical solution of the steady state Atmospheric Diffusion equation for stable conditions
    Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2014
    Co-Authors: Luiz Claudio Gomes Pimentel, J Perez S Guerrero, Ana Graciela Ulke, Fernando P Duda, P Heilbron F L Filho
    Abstract:

    In this work, the performance of a unified formal analytical solution for the simulation of Atmospheric Diffusion problems under stable conditions is evaluated. The eigenquantities required by the formal analytical solution are obtained by solving numerically the associated eigenvalue problem based on a newly developed algorithm capable of being used in high orders and without missing eigenvalues. The performance of the formal analytical solution is evaluated by comparing the converged predicted results against the observed values in the stable runs of the Prairie Grass experiment as well as the simulated results available in the literature. It was found that the developed algorithm was efficient and that the convergence rate depends on the stability condition and the considered parametrizations for wind speed and turbulence. The comparisons among predicted and observed concentrations showed a good agreement and indicate that the considered dispersion formulations are appropriate to simulate dispersion under slightly to moderate Atmospheric stable conditions.

  • a unified analytical solution of the steady state Atmospheric Diffusion equation
    Atmospheric Environment, 2012
    Co-Authors: J Perez S Guerrero, Luiz Claudio Gomes Pimentel, Jose Francisco De Oliveirajunior, P Heilbron F L Filho, Ana Graciela Ulke
    Abstract:

    Abstract A unified analytical solution of the steady-state Atmospheric Diffusion equation for a finite and semi-infinite/infinite media was developed using the classic integral transform technique (CITT) which is based on a systematized method of separation of variable. The solution was obtained considering an arbitrary mean wind velocity depending on the vertical coordinate (z) and a generalized separable functional form for the eddy diffusivities in terms of the longitudinal (x) and vertical coordinates (z). The examples described in this article show that the well known closed-form analytical solutions, available in the literature, for both finite and semi-infinite/infinite media are special cases of the present unified analytical solution. As an example of the strength of the developed methodology, the Copenhagen and Prairie Grass experiments were simulated (finite media with the mean wind speed and the turbulent Diffusion coefficient described by different functional forms). The results indicate that the present solutions are in good agreement with those obtained using other analytical procedures, previously published in the literature. It is important to note that the eigenvalue problem is associated directly to the Atmospheric Diffusion equation making possible the development of the unified analytical solution and also resulting in the improvement of the convergence behavior in the series of the eigenfunction-expansion.

P Heilbron F L Filho - One of the best experts on this subject based on the ideXlab platform.

  • assessment of the unified analytical solution of the steady state Atmospheric Diffusion equation for stable conditions
    Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2014
    Co-Authors: Luiz Claudio Gomes Pimentel, J Perez S Guerrero, Ana Graciela Ulke, Fernando P Duda, P Heilbron F L Filho
    Abstract:

    In this work, the performance of a unified formal analytical solution for the simulation of Atmospheric Diffusion problems under stable conditions is evaluated. The eigenquantities required by the formal analytical solution are obtained by solving numerically the associated eigenvalue problem based on a newly developed algorithm capable of being used in high orders and without missing eigenvalues. The performance of the formal analytical solution is evaluated by comparing the converged predicted results against the observed values in the stable runs of the Prairie Grass experiment as well as the simulated results available in the literature. It was found that the developed algorithm was efficient and that the convergence rate depends on the stability condition and the considered parametrizations for wind speed and turbulence. The comparisons among predicted and observed concentrations showed a good agreement and indicate that the considered dispersion formulations are appropriate to simulate dispersion under slightly to moderate Atmospheric stable conditions.

  • a unified analytical solution of the steady state Atmospheric Diffusion equation
    Atmospheric Environment, 2012
    Co-Authors: J Perez S Guerrero, Luiz Claudio Gomes Pimentel, Jose Francisco De Oliveirajunior, P Heilbron F L Filho, Ana Graciela Ulke
    Abstract:

    Abstract A unified analytical solution of the steady-state Atmospheric Diffusion equation for a finite and semi-infinite/infinite media was developed using the classic integral transform technique (CITT) which is based on a systematized method of separation of variable. The solution was obtained considering an arbitrary mean wind velocity depending on the vertical coordinate (z) and a generalized separable functional form for the eddy diffusivities in terms of the longitudinal (x) and vertical coordinates (z). The examples described in this article show that the well known closed-form analytical solutions, available in the literature, for both finite and semi-infinite/infinite media are special cases of the present unified analytical solution. As an example of the strength of the developed methodology, the Copenhagen and Prairie Grass experiments were simulated (finite media with the mean wind speed and the turbulent Diffusion coefficient described by different functional forms). The results indicate that the present solutions are in good agreement with those obtained using other analytical procedures, previously published in the literature. It is important to note that the eigenvalue problem is associated directly to the Atmospheric Diffusion equation making possible the development of the unified analytical solution and also resulting in the improvement of the convergence behavior in the series of the eigenfunction-expansion.

J Perez S Guerrero - One of the best experts on this subject based on the ideXlab platform.

  • assessment of the unified analytical solution of the steady state Atmospheric Diffusion equation for stable conditions
    Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2014
    Co-Authors: Luiz Claudio Gomes Pimentel, J Perez S Guerrero, Ana Graciela Ulke, Fernando P Duda, P Heilbron F L Filho
    Abstract:

    In this work, the performance of a unified formal analytical solution for the simulation of Atmospheric Diffusion problems under stable conditions is evaluated. The eigenquantities required by the formal analytical solution are obtained by solving numerically the associated eigenvalue problem based on a newly developed algorithm capable of being used in high orders and without missing eigenvalues. The performance of the formal analytical solution is evaluated by comparing the converged predicted results against the observed values in the stable runs of the Prairie Grass experiment as well as the simulated results available in the literature. It was found that the developed algorithm was efficient and that the convergence rate depends on the stability condition and the considered parametrizations for wind speed and turbulence. The comparisons among predicted and observed concentrations showed a good agreement and indicate that the considered dispersion formulations are appropriate to simulate dispersion under slightly to moderate Atmospheric stable conditions.

  • a unified analytical solution of the steady state Atmospheric Diffusion equation
    Atmospheric Environment, 2012
    Co-Authors: J Perez S Guerrero, Luiz Claudio Gomes Pimentel, Jose Francisco De Oliveirajunior, P Heilbron F L Filho, Ana Graciela Ulke
    Abstract:

    Abstract A unified analytical solution of the steady-state Atmospheric Diffusion equation for a finite and semi-infinite/infinite media was developed using the classic integral transform technique (CITT) which is based on a systematized method of separation of variable. The solution was obtained considering an arbitrary mean wind velocity depending on the vertical coordinate (z) and a generalized separable functional form for the eddy diffusivities in terms of the longitudinal (x) and vertical coordinates (z). The examples described in this article show that the well known closed-form analytical solutions, available in the literature, for both finite and semi-infinite/infinite media are special cases of the present unified analytical solution. As an example of the strength of the developed methodology, the Copenhagen and Prairie Grass experiments were simulated (finite media with the mean wind speed and the turbulent Diffusion coefficient described by different functional forms). The results indicate that the present solutions are in good agreement with those obtained using other analytical procedures, previously published in the literature. It is important to note that the eigenvalue problem is associated directly to the Atmospheric Diffusion equation making possible the development of the unified analytical solution and also resulting in the improvement of the convergence behavior in the series of the eigenfunction-expansion.

Luiz Claudio Gomes Pimentel - One of the best experts on this subject based on the ideXlab platform.

  • assessment of the unified analytical solution of the steady state Atmospheric Diffusion equation for stable conditions
    Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2014
    Co-Authors: Luiz Claudio Gomes Pimentel, J Perez S Guerrero, Ana Graciela Ulke, Fernando P Duda, P Heilbron F L Filho
    Abstract:

    In this work, the performance of a unified formal analytical solution for the simulation of Atmospheric Diffusion problems under stable conditions is evaluated. The eigenquantities required by the formal analytical solution are obtained by solving numerically the associated eigenvalue problem based on a newly developed algorithm capable of being used in high orders and without missing eigenvalues. The performance of the formal analytical solution is evaluated by comparing the converged predicted results against the observed values in the stable runs of the Prairie Grass experiment as well as the simulated results available in the literature. It was found that the developed algorithm was efficient and that the convergence rate depends on the stability condition and the considered parametrizations for wind speed and turbulence. The comparisons among predicted and observed concentrations showed a good agreement and indicate that the considered dispersion formulations are appropriate to simulate dispersion under slightly to moderate Atmospheric stable conditions.

  • a unified analytical solution of the steady state Atmospheric Diffusion equation
    Atmospheric Environment, 2012
    Co-Authors: J Perez S Guerrero, Luiz Claudio Gomes Pimentel, Jose Francisco De Oliveirajunior, P Heilbron F L Filho, Ana Graciela Ulke
    Abstract:

    Abstract A unified analytical solution of the steady-state Atmospheric Diffusion equation for a finite and semi-infinite/infinite media was developed using the classic integral transform technique (CITT) which is based on a systematized method of separation of variable. The solution was obtained considering an arbitrary mean wind velocity depending on the vertical coordinate (z) and a generalized separable functional form for the eddy diffusivities in terms of the longitudinal (x) and vertical coordinates (z). The examples described in this article show that the well known closed-form analytical solutions, available in the literature, for both finite and semi-infinite/infinite media are special cases of the present unified analytical solution. As an example of the strength of the developed methodology, the Copenhagen and Prairie Grass experiments were simulated (finite media with the mean wind speed and the turbulent Diffusion coefficient described by different functional forms). The results indicate that the present solutions are in good agreement with those obtained using other analytical procedures, previously published in the literature. It is important to note that the eigenvalue problem is associated directly to the Atmospheric Diffusion equation making possible the development of the unified analytical solution and also resulting in the improvement of the convergence behavior in the series of the eigenfunction-expansion.

Lynn M Hildemann - One of the best experts on this subject based on the ideXlab platform.

  • a generalized mathematical scheme to analytically solve the Atmospheric Diffusion equation with dry deposition
    Atmospheric Environment, 1997
    Co-Authors: Jinsheng Lin, Lynn M Hildemann
    Abstract:

    A generalized mathematical scheme is developed to simulate the turbulent dispersion of pollutants which are adsorbed or deposit to the ground. The scheme is an analytical (exact) solution of the Atmospheric Diffusion equation with height-dependent wind speed and eddy diffusivities, and with a Robin-type boundary condition at the ground. Unlike published solutions of similar problems where complex or non-programmable (e.g., hypergeometric or Kummer) functions are obtained, the analytical solution proposed herein consists of two previously derived Green's functions (modified Bessel functions) expressed in an integral form that is amenable to numerical integration. In the case of invariant wind speed and turbulent eddies with height (i.e., Gaussian deposition plume), the solution reduces to an equivalent well-known heat conduction solution. The physical behavior represented by the Green's functions comprising the solution can be interpreted. This generalized scheme can be modified further to account for inversion effects or other meteorological conditions. The solution derived is useful for examining the accuracy and performance of sophisticated numerical dispersion models, and is particularly suitable for modeling the transport of pollutants undergoing strong surface adsorption or high depositional losses.

  • Analytical solutions of the Atmospheric Diffusion equation with multiple sources and height-dependent wind speed and eddy diffusivities
    Atmospheric Environment, 1996
    Co-Authors: Jinsheng Lin, Lynn M Hildemann
    Abstract:

    Abstract Three-dimensional analytical solutions of the Atmospheric Diffusion equation with multiple sources and height-dependent wind speed and eddy diffusivities are derived in a systematic fashion. For homogeneous Neumann (total reflection), Dirichlet (total adsorption), or mixed boundary conditions, the solutions for a single source are comprised of three components: a source strength, a crosswind dispersion factor, and a vertical dispersion factor. The two dispersion factors together constitute a Green's function—the concentration response due to a unit disturbance (source). When the general point source Green's functions are derived for a bounded domain (inversion effect) with various boundary conditions and arbitrary power-law profiles for wind speed and eddy diffusivities, previously published equations are found to be simplified versions of this more general case. A methodology based on the superposition of Green's functions is proposed, which enables the estimation of ambient concentrations not only from a single source, but also from multiple point, line, or area releases.