Vladimíra Michalcová

Numerical and Experimental Investigations of Air Flow Turbulence Characteristics in the Wind Tunnel Contraction

Flow characteristics contraction of rectangular cross-section are investigated numerically and experimentally so as to gain an additional insight into the contraction design. They observed velocity field and turbulent intensity in the area of contraction and downstream of it. Individual numerical models sofware Ansys Fluent are evaluated and compared with measurements in a wind tunnel.

Effect of Non-Uniform Temperature Distribution over the Cross-Section in Steel Frame Structure

The paper deals with the effect of non-uniform temperature over the cross-section in the steel frame structure under fire loading. The unequal temperature distribution causes additional bending moments in statically indeterminate structures. Numerical results of thermal and structural analysis from the commercial computer software ANSYS are compared with the experimental measurements on the steel frame exposed to high temperature.

MODELS OF LOAD ON BULDINGS FROM THE EFFECTS OF THE FLOW FIELD

Abstracts Article describes two different approaches of the solution of benchmark solution of bluff aerodynamic, which is the solution of wind pressures upon the cube exposed to the effects of air flow field. Physical modeling is carried out at the wind tunnel of the Institute of Theoretical and Applied Mechanics in Telč whereas numerical modeling is performed at the Faculty of Civil Engineering, VSB Technical University of Ostrava of software using Ansys Fluent.

Numerical Modelling of Air Flow Attributes in a Contractions Chamber

Abstract The article describes air flow turbulent attributes in the enclosed chamber of a rectangular cross-section contraction for the purpose of confirming its optimal shape. The task is solved numerically using Ansys Fluent software. Right models were selected based on the evaluated results at a contractions outlet which were compared to the physics experiment

Numerical Models of Wind Effects on Temperature Loaded Object

Wind climate influencing wind loads on buildings and other structures, as well as the dispersion of pollutants from various surfaces is essentially determined by small-scale motions and processes occurring in the atmospheric boundary layer (ABL). The physical and thermal properties of the underlying surface, in conjunction with the dynamics and thermodynamics of the lower atmosphere influence the distribution of wind velocity in thermally stratified ABL. Atmospheric turbulence is characterized by a high degree of irregularity, three-dimensionality, diffusivity, dissipation, and a wide range of motion scales. This article describes a change of selected turbulent variables in the surroundings of flow around a thermally loaded object. The problem is solved numerically in Ansys Fluent 13.0 software using LES (Large eddy simulation) models as well as the Transition SST (Shear Stress Transport) model that is able to take into account the difference between high and low turbulence at the interface between the wake behind an obstacle and the free stream. The results are mutually compared and verified with experimental measurements in the wind tunnel.

Numerical and Experimental Models of the Thermally Stratified Boundary Layer

Abstract The article describes a change of selected turbulent variables in the surroundings of a flow around thermally loaded object. The problem is solved numerically in the software Ansys Fluent using a Transition SST model that is able to take into account the difference between high and low turbulence at the interface between the wake behind an obstacle and the free stream. The results are verified with experimental measurements in the wind tunnel.

Numerical Calculation of Aerodynamic Roughness of Chimney Jacketed with Corrugated Sheets

Abstract The article deals with the influence of a shape of smokestack casing on the total load from wind effects. It describes possibilities of defining an equivalent aerodynamic roughness and aerodynamic drag coefficient for numerical modelling of the flow around a circular cylinder. The aim of this study is to solve the force coefficient for the smokestack of a cylindrical shape, which is jacketed with shaped sheets. The flow around a smokestack is solved in the ANSYS Fluent software using the DES model.

Numerical Calculation of the Force Coefficient for Cylindrical Shape Smokestack Covered with Corrugated Iron

The article deals with the influence of a shape of the smokestacks casing on the final load from wind effects. It describes possibilities of defining an equivalent aerodynamic roughness and aerodynamic drag coefficient for numerical modelling of the flow around a circular cylinder. The aim is to determine the force coefficient for a smokestack of a cylindrical shape, which is sheeted with corrugated sheet metal. The flow around a smokestack is solved in software Ansys Fluent using the DES model.

Numerical and Experimental Modelling of an Air Flow Field in the Chamber of a Rectangular Cross-Section Contraction

The article describes the study of turbulent characteristics in the enclosed chamber of a rectangular corss-section nozzle using numerical calculations. Suitable Ansys Fluent software models were selected based on the measurements results comparison in an aerodynamic tunnel as the fluid exits the nozzle. Special attention is paid to profile velocity near the peripheral wall of the observed enclosed chamber in order to confirm the optimal shape of the contraction and thus take steps towards a high quality velocity field.

Numerical Simulation of Influence Atmospheric Boundary Layer on the Low-Oxidation Progress in the Coal Stockpile

Numerical Simulation of Influence Atmospheric Boundary Layer on the Low-Oxidation Progress in the Coal Stockpile The paper deals with formulation of CFD simulation, which describes fluid flow in atmospheric boundary layer in coal stockpile surround. The paper presents preliminary phases of global project, which aim to spontaneous ignition of coal matter in coal stockpile and coal dump. First part of the global task is focused on generation of Earths surface topology on the basis of GIS data. Second task is focused on simplification of simulation domain and reduction of mesh size by substitution of mine building by porous subdomain. Simulations of flow in boundary layer include only eight dominant directions of wind which are specified by means of wind rose. The FFT analysis is applied to wind direction, intensity and temperature too. Spectrum of velocity and temperature were used to transient CFD simulation with real time 1 month. Numerická Simulace Vlivu Mezní Vrstvy Atmosféry na Rozvoj Nízkoteplotní Oxidace ve Skládce Uhlí Článek popisuje proudění větru v mezní vrstvě atmosféry kolem skládky uhlí. Tato úloha představuje dílčí úsek projektu, který řeší rozvoj nízkoteplotní oxidace ve skládkách uhlí a odvalech. Pozornost je věnována také tvorbě povrchu v okolí skládky na základě GIS dat, a následnému zjednodušení geometrie nahrazením budov porézní oblastí. Simulace proudění zahrnuje 8 dominantních směrů větrné růžice definovaných střední rychlostí. Pomocí FFT (fourierova analýza) byla provedena analýza složek okamžité rychlosti a teploty. Spektrum rychlosti a teploty v intervalu 1 měsíce bylo použito k nestacionární simulaci proudění v okolí reálné skládky uhlí.