Wave lift on subsea pipeline analysis

Dear all,

I am performing a calculation relevant to a subsea pipeline.
In order to clear how CAESAR wave load modeler works, I run some simplified models to isolate the forces due to wave only.
The simplified model is vertically supported by unidirectional frictionless restraints, horizontally restrained by three guides only, frictionless also, and is subject to wave + current acting in perpendicular direction to pipeline axis.
Analysing restraints reactions, it is clear the presence of two distributed loads due to wave: a horizontal load and a vertical load.
The horizontal load is acting according to direction of input wave and current.
The vertical load is acting upward in some cases, downward in others, but it is not clear the correlation between wave data, pipeline level from seabed and direction of vertical wave load.
Can someone give me some suggestion on this topic?

Thanks in advance.

P72

The transverse force (erroneously termed "lift") is determined based on the fluid particle velocity vector. Depending on where you are in the wave, sometimes the velocity is positive, sometimes negative. Therefore, the direction of the transverse force can vary.

Richard,

thanks for your answer.
The point is that I don't know where I am in the wave, since this will be randomly distributed across pipeline route.
Having a vertical upward or downward action heavily affects loads acting on supports, free spans and son on.
What could be according to your experience a way to be always conservative on this subject?

Regards,

P72