Problem:

I have created two models in AutoPIPE. The second model is the mirror model of the first model (I just rotate the model by 180 degree as per attached file). The wave and current that I applied for U1 and U2 are the same in magnitude but in opposite direction (+z and -z). I was expecting the results for Model 1 + U1 case and Model 2 + U2 are the same and similarly the result for Model 1 + U2 case is the same as Model 2 + U1 case. However, the results that I obtained look very different especially while I was checking the displacement based on GT1P1U1 & GT1P1U2 near the U Loop

Is this normal?

Isn't it two identical line will give identical answer?

Solution:

In this user's case:

The results may be different. When running a wave analysis, the wave length is calculated based on the input parameters of the wave load dialog screen. Wave length/phase has a significant effect on the load case results.

When you rotated the model, each point may now be in a different location of the wave length or phase position. As a result, this would cause different results.

You can see what wave length was calculated by AutoPIPE: after completing a static Analysis, look at the Analysis Summary of the output report.

Suggest, after rotating the model; align the model to cause the analysis to be performed at the same phase of the wave length.

See Also

"Displacement" sub report

Bentley AutoPIPE