How can I load a Cp airfoil specific distribution to a mesh

Piercarlo Marchegiani
Piercarlo Marchegiani Altair Community Member
edited October 2020 in Community Q&A

Hi! 

The problem is the following, I am looking to introduce a pressure distribution onto an airfoil. 

I have the Cp values for specific points that doesn´t match my mesh nodes because they were not obtained through a CFD of the airfoil. 

The problem is the same for the Cf values. 

I will attach the excel with the values. 

At first I thought graphing this values, dividing them into functions that I could aproxximate well with trend lines and introduce this functions into the respective nodes that I was selecting by hand. This demands a lot of time and at the end I discovered that the trend lines were not good enough unless I use 15 decimals, thing that exceeds the space to put equations by hypermesh. 

imageimage

I will attach the model also 

image
PS: I dont know why I cant load any images.

 

Hope you understood and thank you for your time.

 

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Answers

  • Adriano Koga_20259
    Adriano Koga_20259 New Altair Community Member
    edited October 2020

    I'm sorry. Could you describe what solver are you trying to use? Is it structural?

    Do you need to map pressures into a structural model?

     

    If yes, one tool that could help you is 'Fields' in HyperMesh. Take a look at its documentation in HyperMesh help section, please.

  • Piercarlo Marchegiani
    Piercarlo Marchegiani Altair Community Member
    edited October 2020

    I'm sorry. Could you describe what solver are you trying to use? Is it structural?

    Do you need to map pressures into a structural model?

     

    If yes, one tool that could help you is 'Fields' in HyperMesh. Take a look at its documentation in HyperMesh help section, please.

    I am using Optistruct. 

    Yes I need to map pressures/forces into a structural model. The problem is I have the values in specific points tha doesnt match the mesh nodes, the only option I have is to put the forces one by one but it is not feasible due to the amount of points. 

    I red the help in fields. Do you know how I can introduce the forces through bulk data or via text files? 

     

     

  • Piercarlo Marchegiani
    Piercarlo Marchegiani Altair Community Member
    edited October 2020

    I am using Optistruct. 

    Yes I need to map pressures/forces into a structural model. The problem is I have the values in specific points tha doesnt match the mesh nodes, the only option I have is to put the forces one by one but it is not feasible due to the amount of points. 

    I red the help in fields. Do you know how I can introduce the forces through bulk data or via text files? 

     

     

    Optistruct for linear static analysis 

     

  • Piercarlo Marchegiani
    Piercarlo Marchegiani Altair Community Member
    edited October 2020

    I tried using linear interpolation, but I need one coordinate to be always normal to the surface and this doesnt give me this option I would need to determine the coordinates one by one

  • Adriano Koga_20259
    Adriano Koga_20259 New Altair Community Member
    edited October 2020

    I am using Optistruct. 

    Yes I need to map pressures/forces into a structural model. The problem is I have the values in specific points tha doesnt match the mesh nodes, the only option I have is to put the forces one by one but it is not feasible due to the amount of points. 

    I red the help in fields. Do you know how I can introduce the forces through bulk data or via text files? 

     

     

    There are examples in the documentation:

    I would try mapping as pressures.

    image

  • Adriano Koga_20259
    Adriano Koga_20259 New Altair Community Member
    edited October 2020

    I tried using linear interpolation, but I need one coordinate to be always normal to the surface and this doesnt give me this option I would need to determine the coordinates one by one

    Maybe u,v parametric mapping in Fields might help you, then. Not quite sure.

  • tinh
    tinh Altair Community Member
    edited October 2020

    Hi @Piercarlo Marchegiani 

    I think trend line is not a good idea, because as we can see, it is overfitting!

    You should take position X of ploads in the model to the excel sheet, and then calculate corresponding cp, cd by interpolation.

    example, your excel sheet:

    x      cp

    0      1.5

    0.1   1.7

    0.2   1.9

    0.3   1.95

    your ploads position in model: X = 0.13

    => cp = (X-0.1)/(0.2-0.1)*(1.9-1.7)+1.7  (linear)

     

    If you can write a tcl script to do that, it will save much time.