Seabed Best Practice

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Seabed Best Practice

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1.It is worth highlighting that the friction coefficients on the Seabed Component are introduced at the end of a normal static analysis sequence (during the friction static step) meaning that they only take effect in subsequent restarts/dynamics. This means that if you want to check the interaction between current loading and seabed friction then you should apply the current loading in a restart analysis.

2.Remember that by default the pipe centreline rests on the seabed rather than the pipe contact diameter (legacy behaviour). This behaviour is only an issue for shallow water installations where the pipe diameter is a certain percentage of the water depth. In such situations, you can change the default approach and instruct PipeLay to account for the contact diameter by setting the Use Pipe Contact Diameter option on the Seabed component to Yes.

3.If you are specifying a very large elastic seabed stiffness (e.g. > 10000 kN/m/m) then consider using a rigid seabed instead for simplicity.

4.The default characteristic lengths for friction modelling (~ 3m) may be too large for shallow water analysis and so you may wish to specify reduced length values in such cases.

5.For an arbitrary seabed ensure that the arbitrary seabed file (ASF) direction is consistent with the provided seabed profile. An ascending direction is with respect to the X=0 datum whereas a descending direction is with respect to the mean water line.

6.For an arbitrary seabed it may be necessary to reduce the maximum element lengths on the Constants dialog of the Project component to match the distance between the sampling points on the seabed, otherwise there is a risk of certain seabed features not being recognised in the analysis due to lack of contact nodes around the features.