Luděk Beneš

Numerical Simulation of the Towing Tank Problem Using High Order Schemes

The article deals with the numerical simulation of 2D and 3D unsteady incompressible flows with stratifications. The mathematical model is based on the Boussinesq approximation of the Navier-Stokes equations. The flow field in the towing tank with a moving sphere is modelled for a wide range of Richardson numbers. The obstacle is modeled via appropriate source terms. The resulting set of partial differential equations is then solved by the fifth-order finite difference WENO scheme, or by the second-order finite volume AUSM MUSCL scheme. For the time integration, the second-order BDF method was used. Both schemes are combined with the artificial compressibility method in dual time.

Numerical Modelling of Pollution Dispersion in 3D Atmospheric Boundary Layer

The main goal of this work is to present the applicable models and numerical methods for solution of flow and pollution dispersion in 3D Atmospheric Boundary Layer (ABL). Mathematical models are based on the system of Reynolds averaged Navier-Stokes equations and its simplifications. The sets of governing equations are completed by the transport equations for passive impurities and potential temperature. A simple algebraic turbulent closure model is used. The thermal stability phenomenon is taken into account. For each mathematical model a numerical scheme based on finite-difference or finite-volume discretization is proposed and discussed. Some results of numerical tests are presented for pollution dispersion from point sources and flows over simple geometries.

Numerical Simulation of Flow and Pollution Dispersion in the Area of Opencast Coal Mine

This paper presents some of the results of numerical simulation of flow and pollution dispersion in the proximity of coal deposit placed in the area of opencast coal mine. The mathematical model is based on Reynolds averaged Navier‐Stokes equations for incompressible flows. Turbulent closure of the model is obtained by simple algebraic turbulence model. The numerical solution is carried out by the semi‐implicit finite‐difference scheme. The 3D results are presented for the flow in real terrain including simulated obstacles. Model sensitivity is studied with respect to simulated obstacle size and shape.

CFD Optimization of a Vegetation Barrier

In this study we deal with a problem of particulate matter dispersion modelling in a presence of a vegetation. We present a method to evaluate the efficiency of the barrier and to optimize its parameters. We use a CFD solver based on the RANS equations to model the air flow in a simplified 2D domain containing a vegetation block adjacent to a road, which serves as a source of the pollutant. Modelled physics captures the processes of a gravitational settling of the particles, dry deposition of the particles on the vegetation, turbulence generation by the road traffic and effect of the vegetation on the air flow. To optimize the effectivity of the barrier we employ a gradient based optimization process. The results show that the optimized variant relies mainly on the effect of increased turbulent diffusion by a sparse vegetation and less on the dry deposition of the pollutant on the vegetation.

Modelling the Effects of a Vegetation Barrier on Road Dust Dispersion

Atmospheric particulate matter (PM) is a well known risk to human health. Vehicular traffic is one of the major sources of particulates in an urban setting.We study a problem of road dust dispersion. Using CFD solver based on RANS equations, we investigate the effect of a vegetation barrier on the concentration of airborne PM induced by road traffic. Simplified 2D model of a porous obstacle adjacent to a road source of two classes of particles serves as an idealization of a real-world situation.Filtering efficiency of the barrier is investigated under varying atmospheric conditions. Our model indicate that the efficiency decreases for increasing wind speed. Effect of atmospheric stratification on~the~air quality behind the barrier is shown to be highly dependent on the wind speed.

Modelling of the Influence of Vegetative Barrier on Concentration of PM10 and PM2,5 from Highway

The influence of different types of the vegetative barrier near a highway on dustiness was studied. Transport, dispersion and sedimentation of pollutants PM10 and PM2.5 emitted from the highway was numerically simulated. Mathematical model was based on the Navier-Stokes equations for turbulent fluid flow in Boussinesq approximation. The AUSM-MUSCL scheme in finite volume formulation on structured orthogonal grid was used.The influence of the shape of the barrier and of its obstructing properties on the concentration of pollutants was studied.

Modelling of the Influence of Vegetative Barrier on Concentration of PM10 from Highway

The influence of different types of the vegetative barrier near a highway on dustiness was studied. Transport and dispersion of pollutants PM10 emitted from the highway were numerically simulated. Mathematical model was based on the Navier-Stokes equations for turbulent fluid flow in Boussinesq approximation. The AUSM-MUSCL scheme in finite volume formulation on structured orthogonal grid was used.

Numerical Modeling of Stably Stratified Fluid Flow

The article deals with the 2D numerical simulation of the stratified incompressible flows behind the moving thin horizontal strip in the towing tank and over the sinusoidal hill. The mathematical model is based on the Boussinesq approximation of the Navier–Stokes equations. The resulting set of PDE’s is then solved by two different numerical methods. Different boundary conditions are tested.

Numerical simulation of the neutrally stratified ABL flow over complex geometry

The paper deals with a mathematical and numerical study of the Atmospheric Boundary Layer (ABL) flow over a complex topography represented either by part of the Giant mountains or by a surface brown coal mine and a coal depot, both located in the North Bohemia. Various types of protective obstacles have been tested and compared, mainly with respect to the reduction of dustiness in the latter case. The mathematical model is based on system of Reynolds Averaged Navier-Stokes (RANS) equations for viscous and incompressible flow. The artificial compressibility method was used. The numerical method is based either on the finite-volume explicit scheme or on a semi-implicit finite-difference scheme. A simple algebraic turbulence model is applied to close the governing system of equations. Moreover, an additional transport equation for a passive pollutant has been considered.

On Some High Resolution Schemes for Stably Stratified Fluid Flows

The aim of this paper is to present some high-resolution numerical methods in the context of the solution of stably stratified flow of incompressible fluid. Two different numerical methods are applied to a simple 2D test case of wall bounded flow and results are compared and discussed in detail with emphasize on the specific features of stratified flows. The two numerical methods are the AUSM finite–volume scheme and the high order compact finite-difference scheme.