In the tab Run definition the scenario of the run is defined.
First, a configuration has to be selected. This is done by means of a pull-down menu showing all the available configurations in the project. Second, an environment has to be selected. Again, this is done by means of a pull-down menu showing all the available environments in the project.
Normally, the time simulation step is 0.5 seconds. By choosing the skip factor of 1, the logging interval is the same as the simulation time step. If the simulation time step is small, a logging file will be large. To reduce the file size, the logging skipping factor can be increased.
Start-off and swell up periods
The total simulation time can be subdivided into four periods:
- Start-up time for constant environmental forces (T1)
- Simulation time with constant forces (T2)
- Start-up time with dynamic forces (T3)
- Simulation time with dynamic forces (T4)
In the first period, only constant environmental forces are applied. The forces are gradually applied with a start-up function such that they slowly increase from zero towards their maximum value at the end of the start-up period. The use of constant forces implies that:
- Wind gust is not applied (only mean wind force based on mean wind speed)
- The first-order wave forces and varying wave drift forces are not applied (only the mean wave drift forces)
The length of this period can be zero.
In the second period, other constant forces are applied. The length of this period can be zero.
In the third and fourth period, the dynamic forces are included (wind gust, first-order wave forces and slowly varying wave drift forces). However, during the third period, the dynamic part of the force is gradually applied again with a start-up function. The length of the third period can be zero.
Below, an example of the build-up of a typical force is shown.
The first three periods T1, T2 and T3 of the simulation are excluded from the statistics. The statistics are calculated during the fourth period T4, when all forces are fully applied.