The study of interaction between two rigid cylinders elastically mounted and submitted to current shows that the response of the downstream cylinder is very different from a single one. Except when the cylinders are shifted of an angle of 90 deg, the downstream cylinder is strongly affected by wake effects. In spite of an increase of the oscillation amplitudes of the downstream cylinder, there is no real lock-in at the expected reduced velocity. However the fluctuations of the transverse motions are larger than those of the upstream cylinder for reduced velocity greater than 10. In addition these motions increase after the lock-in of the upstream cylinder and they can sometimes reach more than 2 diameters for the highest velocity. The upstream cylinder is not too much disturbed by the downstream cylinder in its wake. Its response is similar to a single cylinder for reduced velocity lower than 17. For higher velocity, sudden changes of behaviour appear which can cause collisions between cylinders. The numerical study shows that first simulations obtained with the CFD code Fluent are in quite good agreement with bibliography results. Hydrody-namic coefficients like added mass coefficient and drag coefficient as well as the motions of the cylinder are correctly reproduced for the lowest reduced velocities. This numerical work is still in progress but it gives good hopes for the following studies.
展开▼
