Numerical Modelling of the Aerodynamic Roughness of Trapezoidal and Corrugated Sheets

摘要

The shape of a covering of smokestacks significantly influences the load from wind effects. In civil engineering practice, particularly for high chimneys, there is often a requirement for their coating with shaped sheet metal as a result of dilatation. The calculation of load effects according to the valid standard only takes into account the size of roughness of the flow around the body, therefore the size of the wave-height sheet regardless of its shape is ignored, which in some cases leads to a substantial increase of the coefficient forces. This paper deals with the possibilities of defining of an equivalent aerodynamic drag coefficient value for flow around a sheathed chimney referred to as the aforementioned coefficient forces. The problem is solved numerically using the finite volume computational fluid dynamics codes in the software ANSYS Fluent. Meshing of the shaped sheathing makes high demands on the number of cells in the computational area currently unrealistic for desktop PCs. The aim is to determine a suitable equivalent aerodynamic roughness of the selected two types of sheet metal with the same wave height. This roughness can be subsequently used for modelling of the required processes in the simplified calculation.