Fluid-structure interaction II

Flows Around Bodies

Underlying Flow Regime 2-14

Test Case Study

Description of the geometrical model and the test section

FSI-PfS-2a consists of a flexible rubber structure with an attached steel weight clamped behind a fixed rigid non-rotating cylinder installed in a water channel (see Fig. 1). The experiments use the same set-up as used in FSI-PfS-1a. As a consequence all channel related parameters suchs as test section geometries, blocking ratio and the working conditions including the inflow Profile remain the same as described in FSI-PfS-1a. The difference in investigations are the changed structure definitions of FSI-PfS-2a. The deformable structure used in the experiment behind the cylinder has a slightly shorter length with $l_{1}\operatorname {=} 0.050\,m(l_{1}/D\approx 2.27)$ . The attached steel weight has a length of $l_{2}\operatorname {=} 0.010\,m(l_{2}/D\approx 0.46)$ and the width w that the addition of $l_{1}$ and $l_{2}$ yield the length $l\operatorname {=} 0.060\,m$ identical to the plate of FSI-PfS-1a. The whole structure including the rigid cylinder, the flexible plate and the steel weight have a width $w\operatorname {=} 0.177\,m(w/D\approx 8.05)$ . Again the small gap of about $1.5\times 10^{-3}\,m$ between the side of the structure and both lateral channel walls is present. In contrast to the rubber material applied in FSI-PfS-1a the rubber used in FSI-PfS-2a has an almost constant thickness $h\operatorname {=} 0.002\,m(h/D\approx 0.09)$ . All parameters of the geometrical configuration of the FSI-PfS-2a benchmark are summarized as follows:

File:Qnet FSI-PfS-2a geo2.png

Test Case Experiments

Provide a brief description of the test facility, together with the measurement techniques used. Indicate what quantities were measured and where.

Discuss the quality of the data and the accuracy of the measurements. It is recognized that the depth and extent of this discussion is dependent upon the amount and quality of information provided in the source documents. However, it should seek to address:

How close is the flow to the target/design flow (e.g. if the flow is supposed to be two-dimensional, how well is this condition satisfied)?

Estimation of the accuracy of measured quantities arising from given measurement technique

Checks on global conservation of physically conserved quantities, momentum, energy etc.

Consistency in the measurements of different quantities.

Discuss how well conditions at boundaries of the flow such as inflow, outflow, walls, far fields, free surface are provided or could be reasonably estimated in order to facilitate CFD calculations

CFD Methods

Provide an overview of the methods used to analyze the test case. This should describe the codes employed together with the turbulence/physical models examined; the models need not be described in detail if good references are available but the treatment used at the walls should explained. Comment on how well the boundary conditions used replicate the conditions in the test rig, e.g. inflow conditions based on measured data at the rig measurement station or reconstructed based on well-defined estimates and assumptions.

Discuss the quality and accuracy of the CFD calculations. As before, it is recognized that the depth and extent of this discussion is dependent upon the amount and quality of information provided in the source documents. However the following points should be addressed: