Modes to find


I have been working on some tanks models with the "Modal" module. I have been collecting good results regarding the modes of the convective mass (within the order of 0.1 to 0.3 Hz), but I have not been doing very well when I need to collect the modal information associated with the impulsive mass. The number of modes that I ask the program for is a bit exaggerated (more than 5000 modes and still don't get the impulsive modes), so I would like to know if there is any possibility to limit this number of modes, i.e. that the program only calculates the modes in one direction only, since a cylindrical tank fortunately has symmetry.

Thanks a lot!!


  • peteroznewmanpeteroznewman Posts: 13,251Member


    I don't know what you mean by "modal information associated with the impulsive mass."

    You get to specify the number of modes the modal solver calculates.

    Maybe someone from ANSYS will have a comment.

  • Esteban_GuajardoEsteban_Guajardo Posts: 8Member

    Hi @peteroznewman

    Im sorry that I didnt answer before... I was away because of work.

    I understand that I get to specify the number of modes, the problem is that I get th modes (or frequencies) in pairs, and the difference between them are really tiny (up to the fourth decimal)

    The impulsive mass of tanks normaly (depending on the dimensions of the tank) will be activated at the higher frencuencies, and because of these differences in them, that I've talked you about, the number of modes that I have to ask is really "a bit much" and still can not get the information for the impulsive frecuencies. I dont know if one can manipulate the tolerances of the decimals in order to reach "engineering results"...maybe truncate decimals to second digit I think is a reasonable way to go. You can see in the image how many 0,75 Hz the program calculates, which is completely useless under my humble point of view.

    I'm really thankful as always... You've been helping me a lot :)

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