The dynamic analysis is a time simulation of.docVIP

Dynamic Analysis The dynamic analysis is a time simulation of the motions of the model over a specified period of time, starting from the position derived by the static analysis. The period of simulation is defined as a number of consecutive stages, whose durations are specified in the data. Various controlling aspects of the model can be set on a stage by stage basis, for example the way winches are controlled, the velocities and rates of turn of vessels and the releasing of lines, links and winches. This allows quite complex operational sequences to be modelled. Before the main simulation stage(s) there is a build-up stage, during which the wave and vessel motions are smoothly ramped up from zero to their full size. Ramping of current is optional (see Current Data). This gives a gentle start to the simulation and helps reduce the transients that are generated by the change from the static position to full dynamic motion. This build-up stage is numbered 0 and its length should normally be set to at least one wave period. The remaining stages, simply numbered 1, 2, 3..., are intended as the main stages of analysis Time is measured in OrcaFlex in seconds. To allow you to time-shift one aspect of the model relative to the others, different parts of the OrcaFlex model have their own user-specified time origins. See the diagram below. For example, simulation time is measured relative to the simulation time origin, which is specified on the Wave page on the environment data form. The simulation time origin is at the end of the build-up stage, so negative simulation time is the build-up stage and the remaining stages are in positive simulation time. The figure below shows a simulation using a build-up of 10 seconds, followed by two stages of 15 seconds each. By default all of the time origins are zero, so all of the time frames coincide with global time. For most cases this simple situation is all you need, but here is