Simulation methods for dynamic fluid-structure interactions of lightweight flexible structures

In the last decade, the demand for the prediction of complex multi-physics prob-lems such as fluid-structure interaction (FSI) has strongly increased. For the development and improvement of appropriate numerical tools several test case swere designed in order to vali-date the numerical res ults based on experimental reference data [4, 12, 13, 8, 9, 10 ]. Since FSI problems often occur inturbulent flows also in the experiments similar conditions have to be provided. Inthetest - case FSI - PfS- 1a [7] presented in the first contribution to this session, acylinder is used with anattached flexible rubber plate. Theresulting FSI problem is nearly two - dimensionalregarding the phase -averaged flow and thes tructure deformations. Theac - tualtestcase FSI - PfS -3a is the reasonable further development step of this two - -dimensional flow, Which now alsoleads to a significant three - dimensional structure deformation. Thecy linder is replaced by a truncated cone .Similar to FSI - PfS - 1a [7] arubber plate is attachedat the backside. This geometrical setup is exposed to aconstant flowat Re = 32 ,000 which hisin the subcritical regime. Dueto the linearly increasing diameter of the cone the alternating eddies in the wake even become larger resulting incorre - spondingly increasing structural displacements. Owingt o thes echallenging flow and structure effects, this benchmark will be the next step for validating FSI predictions for real applications. The experiments are performed in a water channel with clearly defined and controllable bound - ary and operating conditions. Formeasuring the flowa two - dimensional mono - particle - image velocimetry (PIV) system isapplied. In order to characterize the three - dimensional behaviorof the flow, phase - averaged PIV measurements are performed at three different planes. The structural deformations are measured along a line on the structure surface with atime - resolved laser distance sensor. The resulting FSI problem shows a quasi - periodic deformation behavior so that a phase averaging of the results is reasonable. Byphase - averaging turbulent fluctua-tions are averaged out and thus a comparison with corresponding numerical simulations basedon LES [3] and RANS [12, 13] approaches is possible.