1. Reference problem

1.1. Geometry

\(L=50m\)

\({R}_{i}=1m\)

\({R}_{e}=1.1m\)

\(C\): pivot point of the external structure (pivoting around \(\mathrm{Cx}\))

1.2. Material properties

fluid: density \({\rho }_{1}=1000{\mathrm{kg.m}}^{-3}\); \({\rho }_{2}=750{\mathrm{kg.m}}^{-3}\);

Structure: \({\rho }_{s}=7800\mathrm{kg}/{m}^{3}\); \(E=2.1{10}^{11}\mathrm{Pa}\);; \(\nu =0.3\) (steel).

1.3. Boundary conditions and loads

Fluid:

1. to simulate the permanent flow, a normal speed of \(–4m\mathrm{/}s\) is imposed on the fluid inlet face (by thermal analysis, a normal heat flow equivalent to \(–4\) is imposed);

2. to model the variation in density, a condition of continuity of the flow rate is imposed at the interface;

3. to calculate the fluid disturbance caused by the movement of the external cylinder, a Dirichlet boundary condition is imposed at a fluid node.

Structure:

1. the external cylinder is subjected to a displacement of the type

   

at the nodes of the mesh of this cylinder.