Line Length |
 
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Line Length |
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The line length would be specified as 450m, corresponding to the total riser length shown in the Steep Wave Riser example. Based on the length of a line, and the straight line distance between its start and end locations, Flexcom automatically determines whether the line should be modelled internally using a curved (cable) or a straight section. If the straight line distance between the start and end locations is less than the specified line length, a cable (or several cables) is used. Otherwise the line is modelled using a straight line of nodes and elements. Note that line length is an optional input, and if no length is specified, then the length is equal to the straight line distance between its end points. Obviously cables will be automatically used by Flexcom in the case of the steep wave riser example.
Flexcom will typically use a separate cable to model each subsection of a line which has different structural properties. In the case of a steep wave riser for example, this is perfectly reasonable. However, in very occasional circumstances, it may be desirable to model several discrete subsections using a single catenary representation. For example, if you are modelling a buoyant section of riser which is comprised of standard material supported by numerous discrete buoyancy modules along its length, a single catenary model is preferable. Otherwise a large number of separate cables will be used internally to model what is essentially a simple catenary, and some or all of the individual cables are likely to violate the basic assumptions associated with catenary equations. In such circumstances, you can use the Force Single Catenary option to explicitly request that an entire line is to modelled using one single catenary/cable.