LS Dyna

LS Dyna

ICFD- FSI stress output

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    • Laura Pałys
      Subscriber

      Hi, Does anyone know how I could get the results of scalar shear stresses (in a numerical mesh generated automatically in ICFD). I need these values as a criterion for evaluating a medical device. I found a relationship between stresses and velocity gradient. I wonder how to introduce these equations into LS-DYNA. 

    • Reno Genest
      Ansys Employee

      Hello Laura,

      Have a look at *ICFD_DATABASE_DRAG in the user manual vol III:

      LSDYNA » Manuals (ansys.com)

       

      You can output the drag forces and moments on surfaces. It will split the drap forces into pressures forces (normal to the surface) and viscous forces (tangent to the surface which is what you want). With these forces, you should be able to calculate the shear stresses. Here is what you will find in the manual:

       

      I don't know if it is possible to output shear stresses directly.

       

      Reno.

    • Reno Genest
      Ansys Employee

      Hello Laura,

      You can also fringe the shear vector on the MSMESH part of your choice to visualize the hot spots:

      You can also do this with the MSPOST Explorer:

       

      Reno.

    • Laura Pałys
      Subscriber

      Dear Reno,

      thank you for your response.Unfortunately, I am unable to manage with my problem. I used the DATABASE_DRAG_VOL  (I also put 1 for ELOUT card), but but this is still the value for the surface when I want to compute the same value for each element.

      Do you know how can I get the values of individual components (pressure, velocity) in text form? For this, I would also need information about the size of the surface that the element consists of. Additionally, the simulation is transient and the remeshing follows.

    • Laura Pałys
      Subscriber

      I found an interesting option in the post-processing module. But as I mentioned, I don't know how to generate an ifcdrag file. 

    • Reno Genest
      Ansys Employee

       

      Hello Laura,

      Do you have the *ICFD_DATABASE_DRAG keyword in your model? If so, it should create the following drag ASCII files:

      You can read the drag files with a text editor or post-process with LSPP as follows:

       

      Let me know how it goes.

       

      Reno.

       

    • Laura Pałys
      Subscriber

      Hello Reno,

      ICFD_DATABASE_DRAG works well (I've got icfdraga.dat file for surface), but for ICFD_DATABASE_DRAG_VOL I haven't got any output. 

      Best,

      Laura

       

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