Computational engineering for wind-exposed thin-walled structures

Computational engineering for wind-exposed thin-walled structures 5
250
CFD
18 nodes,
10 elements
CSD
15 nodes,
8 elements
Fig. 5. Discretization of the interface
displacement upper boundary [mm]
200
150
100
50
0
−50
−100
−150
t 1 = 0:025 s
t 2 = 0:0125 s
t 3 = 0:00625 s
−200
0 0.5 1 1.5 2 2.5 3 3.5
time [s]
Fig. 6. Displacement for dierent t
uniform renement was performed in two levels which leads to 13,200
and 105,600 hexaeder elements and 40 or 160 quadrilaterals for the interface,
respectively. The coarsest grid for the CSD simulation consisting of only 2
elements is also shown in Fig. 7. Uniform renement yields surface meshes of
8 or 32 quadrilateral elements for the structure simulation, respectively.
CFD
18 nodes,
10 elements
CSD
6nodes,
2 elements
Fig. 7. Initial interface discretization
displacement upper boundary [mm]
300
250
200
150
100
50
0
−50
−100
−150
CFD10=CSD 2
CFD40=CSD 8
CFD160=CSD 32
−200
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
time [s]
Fig. 8. Displacement for dierent interface
discretizations
Fig.8points out the insucient accuracy of the results corresponding to
the initial interface discretizations and the good agreement of the transient
displacements achieved with the rened meshes. In particular the CSD mesh
consisting only of 2 elements for the y-direction is too coarse to obtain useful
results.
4.2 Vertical plate under a sudden wind gust
The geometry and material properties of the second test case are the same
as before. Fig. 9 shows a cutting plane through the uid domain which is
open with an inlet (left boundary), an outlet (right boundary), and symmetric
boundary conditions at the top as well as in z-direction. At the beginning
of the coupled simulation the uid suddenly accelerates and adopts