Fluid—structure coupling analysis and simulation of a slender structure

Abstract

The analysis of the interaction between the flow and the fluid and an object represents a classical challenge for modern numerical techniques. Current work will concentrate on the case of bluff-body cross-sections featuring sharp corners and a clear predominance of the shape resistance over the friction resistance. For this category of structures the dynamic behaviour of the overall coupled system plays a very important role. In this work, the interest focuses on the behaviour of a beam structure subjected to a flow orthogonal to the beam axis. Under this assumption the flow at two points, at reasonable distance, will present little correlation, which allows to consider the flow at one point as uncoupled from the flow at other points along the same beam. This suggests the possibility of "slicing" the fluid domain in a number of independent two-dimensional planes on each of which the problem can be solved separately. Conceptually the solution on each slice will provide a force density acting on the beam, obtained by integrating the pressure of the fluid over the corresponding cross-section. This can be interpreted as a time-varying distributed load over the beam. The aeroelastic analysis of a slender beam is performed coupling a Navier Stokes Solver with the structural model. In the analysis of the structure is used a monodimensional structural model applicable to thin−walled composite beams, which can have either an open or closed profile with either a single-or multiplecell section. However, in the application example presented here, a steel chimney 90 meters tall is analyzed.