Acusolve - Exhaust Manifold Simulation

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hello Forum,

 

I am a student and am learning how to use acusolve, I would like to know how to make a simulation of an exhaust manifold. I want to know what I have to define so I can have inlet conditions that change by time, do I only need to modify boundary conditions?

 

Thanks,

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Answers

  • ydigit
    ydigit
    Altair Employee
    edited April 2015

    You would need

     

    Global

    -  Auto Solution Strategy- Transient.

    - Multiplier Function

     

    Model-

    - Inflow boundary condition with a multiplier function. This multiplier function defined above

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited April 2015

    You would need

     

    Global

    -  Auto Solution Strategy- Transient.

    - Multiplier Function

     

    Model-

    - Inflow boundary condition with a multiplier function. This multiplier function defined above

     

    Do you have a tutorial on how to use the multiplier function?

  • ydigit
    ydigit
    Altair Employee
    edited April 2015

    This might help you to get started.

    Unable to find an attachment - read this blog

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited April 2015

    This might help you to get started.

    Now I get this error message as I run Acusolve, any tip?

     

    acuSolve: ---------------------- Begin Time Step ----------------------

    acuSolve: Time-Step=    1 ; timeInc= 1.000000e+010 ; time= 0.000000e+000

    acuSolve: *** ASSERTION in Function <fElm3TwfVelSp>

    acuSolve: *** no convergence

    acuSolve: *** ASSERTION in Function <fElm3TwfVelSp>

    acuSolve: *** no convergence

    acuSolve: *** ASSERTION in Function <fElm3TwfVelSp>

    acuSolve: *** no convergence

    acuRun: *** ERROR: error occurred executing acuSolve'

    acuRun: Tue Apr 21 09:03:15 2015
  • ydigit
    ydigit
    Altair Employee
    edited April 2015

    Could you upload the .ACS file?

    It seems you are using the same time step as for steady state. Time Inc = 100000000?

    If you are running transient, also select a realistic time increment.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited April 2015

    what would be a more realistic time step? (I can not upload the file, the forum says I am not permitted to upload that kind of file)

     

    Thanks,

  • ydigit
    ydigit
    Altair Employee
    edited April 2015

    Time step 0.1 sec might be a good starting point.

    Please upload .inp and .Log file. If necessary, rename the extension to .txt.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited April 2015

    Time step 0.1 sec might be a good starting point.

    Please upload .inp and .Log file. If necessary, rename the extension to .txt.

     

    Here it is.

    Unable to find an attachment - read this blog

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited April 2015

    It does not helped the 0.1 seconds, I still have the same error

  • ydigit
    ydigit
    Altair Employee
    edited April 2015

    The problem was the Time  was supposed to be Piecewise Linear.

    With that one change it runs. Input file attached.

     

    BTW, you would need to makes considerable changes to get useful results. Mesh is too coarse to get any accurate results. Also Nodal Output would be have to be changed to lesser value (e.g. 1 or 10), instead of current default 1000.

    If you have not attended any training, I would recommend to visit an AcuSolve training at the nearest Altair location.

    Unable to find an attachment - read this blog

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited April 2015

    The problem was the Time  was supposed to be Piecewise Linear.

    With that one change it runs. Input file attached.

     

    BTW, you would need to makes considerable changes to get useful results. Mesh is too coarse to get any accurate results. Also Nodal Output would be have to be changed to lesser value (e.g. 1 or 10), instead of current default 1000.

    If you have not attended any training, I would recommend to visit an AcuSolve training at the nearest Altair location.

    Thanks,  the Time should be change only in the multiplier function or where else did you put Piecewise Linear

  • ydigit
    ydigit
    Altair Employee
    edited April 2015

    Please compare the .INP file I uploaded with the one you uploaded image/emoticons/default_wink.png' alt=';)' srcset='/emoticons/wink@2x.png 2x' width='20' height='20'>

     

    # +----------------------------------------------------------------------+
    # | Multiplier Function                                                  |
    # +----------------------------------------------------------------------+

    MULTIPLIER_FUNCTION( 'time' ) {
        type                                = piecewise_linear
        curve_fit_values                    = { 0.0, 900.0;
                                                5.0, 900.0;
                                                7.5, 0.0;
                                                10.0, 0.0;
                                                12.5, 900.0; }
        curve_fit_variable                  = time
        evaluation                          = once_per_time_step
        filter                              = none
    }