Getting the axial pressure Answered

Hi there,

I am looking for advice on what would be the most appropriate way to get the axial pressure data from a simulation. I am looking to compare pressure readings from an experiment with a needle hydrophone and I believe there are the following ways to extract pressure data in OnScale but not sure which is the ideal method to use:

1. Extract the mode shape data for pressure at the frequency of interest. However, I am not sure if this would just give the pressure for the last time step or something else?

2. Extrapolate for a specific frequency - same issue as above?

3. Get the pressure with time data for all nodes along the axis of interest, export these results and take the peak to peak amplitude of each signal to be the pressure at that node?

I would really appreciate it if someone could explain the above to me in terms of how one method relates to the other?

Thanks for your time,

Laura Morrison


  • Official comment

    Hi Laura,

    For what you are describing you should use extrapolation (option 2) to get the pressure at an axial distance from the hyrdophone. This will give you a pressure time signal at that node. You can do this by setting up the extrapolation boundary in the .flxinp and then getting the location response in the Post Processor using the generated .flxext and .flxmdl files.

    See the following articles for more details:

    Setting up extrapolation

    How to get location response in the Post Processor

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  • Hi Chloe,

    Thanks for this! 

    I think I need to model the full tank used in the experiment (with quarter symmetry) in order to account for the boundary conditions at the walls of the tank. In this case, rather than extrapolation would it work to get the time history of the pressure at certain nodes along the axis using pout to get the results in the history file?


    Thanks again,


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