Section 2 of this report gives detailed discussions of the present state-of-the-art concerning the 

 vortex-excited oscillations of flexible, cylindrical structures with nominally circular cross-sections. Par- 

 ticular attention is given to the behavior of a cable in a flowing fluid and to the specification of the 

 hydrodynamic forces and the resonant vibration response characteristics. The coherence or phase uni- 

 formity of the vortex shedding due to lock-on also is discussed. The effects of yaw or inclination of the 

 cable, surface roughness, and shear (nonuniform flow) gradients are assessed in terms of their 

 influence on vortex-excited oscillations. 



In Section 3 of the report a discussion is given of recent experimental studies of cable strumming. 

 The physical scales of the experiments range from relatively small flow channels, to large towing chan- 

 nels and to field experiments in the oceanic environment. The field experiments encompass relatively 

 small-scale tests conducted in a tidal inlet and large-scale, deep water tests of moored arrays. 



Analytical models which have been developed for the prediction of cable strumming are discussed 

 in Section 4 of the report. The various modelling approaches taken by different investigators are 

 reviewed, and recommendations are made for applications to the cable design process. Comparisons are 

 made between the model predictions and available experimental data from both laboratory and field 

 scale tests. A discussion is given of the prediction methods and design procedures which have been 

 developed and calibrated for practical applications. The parameters that must be considered in an 

 assessment of the severity of strumming oscillations are defined and step-by-step procedures are given 

 for making such an assessment. 



Computer codes for predicting and modelling cable strumming are described in Section 5. The 

 codes that have been developed for ocean engineering applications comprise two areas of application: 

 the static analysis of cable arrays and the dynamics of marine cables. NATFREQ is a code for calculat- 

 ing natural frequencies, mode shapes, and drag amplification factors for taut cables with attached 

 masses. DESADE and DECEL 1 are two versions of a code that was developed to statically analyze 



