.. _V8.01.106:

**v8.01.106** FDLV106 - Calculation of damping added in annular flow
==============================================================================

**Summary:**

This fluid/structure test involves calculating the mass and damping added to a cylindrical structure subjected to an annular flow that is assumed to be potential. Initially, mass and damping added by the flow on the structure are calculated for various upstream speeds (:math:`4m/s`, :math:`4.24m/s` and :math:`6m/s`), on a 3D model for the fluid and shell for the structure. The structure has a rotational movement around a pivot located at the downstream end of the cylinder with respect to the flow.

The coefficients determined are assigned to a discrete model equivalent to 1 ddl mass-spring-damper, on which a modal analysis is carried out, in order to determine the complex natural frequencies of the system for the various flow velocities:

:math:`4m/s`: amortization,

:math:`4.24m/s`: critical speed, zero damping,

:math:`6m/s`: negative damping, floating.


.. toctree::
    :hidden:

    self

.. toctree::
    :maxdepth: 2
    :numbered:

    Probl_me_de_r_f_rence
    Solution_de_r_f_rence
    Mod_lisation_A
    Synth_se_des_r_sultats