Problem 

 structure 



Isolated 

 pile 



End 



No 

 oscillation 



Calculate V/ND and 

 Rg to determine if 

 in-line or cross-flow 

 oscillation is possible 

 (5.3.1. and 5.3.2.) 



Possible 



oscillation 



Circular 

 sections 

 only 



In-line motion 

 If 2m6 <I.S; 



(See 5.3.1. and 

 5.5.1. for 



unlinked 

 arrays) 



Array of piles 

 or members 



Calculate V/ND and Re for each 

 pile or member to determine 

 if in-line or cross flow oscillation 

 is possible (5.3.1. and 5.3.2.) 

 N should relate to both individual 

 members and overall structure. 

 For members inclined to the 

 flow see 5.4 



Possible 

 oscillation 



No 

 oscillation 



End 



Circular 

 sections only 



Unlinked 

 array 



Linked 

 array 



Lattice 

 structure 



Calculate _rn and 5 



PD- 

 As described in 5.5.4: 

 In-line motion if 

 2S6 



pD 



<\.i 



Less certain criterion for 

 cross-flow motion if wake 

 interaction, but no motion 



if 2m§>30 



Cross-stream motion 



Isolated piles; 

 motion if 



5.3.2 



Unlinked array: 

 Upstream cylinder as 

 isolated cylinder, 

 downstream cylinder 

 motion if 



2m6 <30 

 5.5.1. 



Figure 4.1 Flow diagram of the steps required for the calculation of the response of the structure due to vortex shed- 

 ding; adapted from Hallam, and Wootton (68). Numbers in the boxes refer to relevant sections of reference 68. The 

 same general procedures apply to an analysis of the strumming vibrations of marine cables. 



97 



