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v6.57 apparently missing range of reynolds number option

2022-12-13
2022-12-17
  • Eduarda Coppo

    Eduarda Coppo - 2022-12-13

    Is there a way to do batch analysis using a reynolds range instead of the reynolds list (which seems it's the only option now)? Having to work with a list is not as fast and efficient. Was the range feature removed or is there a way to use it in newer versions? The image I'm attaching shows the range feature I'm talking about

     
  • Stefan

    Stefan - 2022-12-14

    The feature was removed a while ago. Lists are way more useful since the differences in drag coefficient don't scale linearly with the reynolds number. Therefore the fine increments necessary at low reynolds numbers only create unnecessary calculations at higher reynolds numbers when using the range feature.

    Cheers,
    Stefan

     
  • Eduarda Coppo

    Eduarda Coppo - 2022-12-15

    Still trying to understand here (excuse my ignorance). I can make a list that goes from, for example, 50.000 to 500.000 Re with increments of 50.000. In other words, I can emulate the range feature, it'll only be a tedious and manual work. So, I still don't see how lists are more useful.

     
  • Stefan

    Stefan - 2022-12-15

    You could use the list to emulate the range feature, yes.
    However, if you take a look at the polars you will notice that the differences are greater at lower reynolds numbers than at higher reynolds numbers for the same increment.
    For example, the difference in lift and drag coefficient between Re 5e4 and 1e5 is greater than between 3e5 and 5e5 even though the increment is FOUR times larger (see attached image).
    Therefore you need a fine increment at low reynolds numbers to get a good polar mesh. However, if you use THE SAME, FINE increment at high reynolds numbers you only waste computational resources (and time) on polars that don't increase your accuracy (see attached image, difference between Re 5e5 & 5.5e5).
    The list feature lets you work around that by using fine increments at low reynolds numbers and great increments at higher reynolds numbers, giving you pretty much the same accuracy at much lower computational load (time).

    Cheers,
    Stefan

     

    Last edit: Stefan 2022-12-15
    • Eduarda Coppo

      Eduarda Coppo - 2022-12-17

      Makes sense. I get it now. Thanks for taking the time to explain.

       

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