The distribution of pollutants in two urban scale models (point emission source and street canyon with extensive transport) was investigated by means of CO(2) laser photoacoustic spectroscopy in the region of the atmospheric window (9-10 mum). The experimental results of physical modeling are in a good agreement with the numerical calculations performed in the frame of computational fluid dynamic (CFD) modeling. Methanol, ethanol, and ozone (examples of light pollutants), as well as sulfur hexafluoride and 1,2 dichlorethane (examples of heavy pollutants), were selected on the basis of their high resolution spectra acquired by Fourier transform and laser diode spectroscopy.
The twin-screw pump is designed for pumping highly viscous materials in the food industry. Rheological characteristics of materials are important in the specification of design parameters of screw pumps. Analysis of flow in the twin-screw pumps with definition of non-newtonian materials can be made by numerical modelling. CFD generally oriented software ANSYS Fluent and ANSYS Polyflow has been used for modelling. In this study those software’s (ANSYS Fluent and ANSYS Polyflow) were defined for solution of flow in the twin-screw pumps. Results were compared for the same boundary conditions on the inlet and outlet of the 3D model. For definition of the viscosity were used the Nonnewtonian power law. Parameters as consistency coefficient and flow exponent for Nonnewtonian power law were analysed by software ANSYS Fluent and ANSYS Polyflow. Postprocessing form ANSYS Fluent and ANSYS Polyflow were made by contours of field and by graphs.
This article is aimed to define the flow in the annulus. The shaft is deposited in a case which has at inlet and outlet recess. The rotor moves in the case. This movement can be divided into the rotation and precession. It is situation where the rotor rotates around own axis and together moves along the circle. The solution of the problem was the initiative in practice where this type of movement occurs in many components, e.g. sliding journal bearings. The fluid flows in the annulus due to the pressure gradient between inlet and outlet and together takes place rotational movement due to movement of the rotor. Between the liquid and the solid of an interaction which results in a change in the forces. The problem is solved by mathematical CFD solver ANSYS Fluent. Based on the characteristics of the problem has been defined corresponding to a mathematical model for the selected types of liquids - VG 32 mineral oil, VG 150 mineral oil and water. Individual variants of used liquids are compared with each other courses of forces acting on the rotor under the same boundary conditions.
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