2. Benchmark solution

2.1. Calculation method used for the reference solution

The results obtained with two fluid excitation zones, of the same nature, and distributed over each half of the tube, are compared with those obtained with a single excitation zone defined over the entire tube.

For fluid-elastic coupling forces, comparisons are made on the variations in frequency and reduced damping of the structure, as a function of the flow speed. Several calculations are carried out with uniform speed profiles on \([\mathrm{AD}]\), or in stairs (uniform on \([\mathrm{AB}]\) and uniform on \([\mathrm{CD}]\)), and different types of network (configurations VISCACHE 1 and CLOTAIRE). The comparisons were carried out, for a flow speed of \(\mathrm{1,5}m/s\), for mode 2.

With regard to the turbulent excitations, the standard deviations of the displacement calculated from the vibratory response spectra were compared. These comparisons were also carried out for structures where the speed profiles were uniform on \([\mathrm{AD}]\), or stepped (uniform on \([\mathrm{AB}]\) and uniform on \([\mathrm{CD}]\)). They were carried out at one of the two nodes located in the middle of the tube (node 100), where the differences are maximum.