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Comparison between CFD results and experimental data

  1. Jan 30, 2015 #1
    Hi everybody,
    my question is not properly about CFD but mainly about Fluid Dynamics itself. I have performed a RANS simulation of a round jet of methane and air and now I'd like to compare those results to some experiments. Unfortunately there aren't papers about experimental data for methane/air jets but mainly I'm finding a lot of data about round jets of water with different nozzle dimensions. So my question is: can I compare those experimental data with my results if the Reynolds number are the same? Or is it highly incorrect?

    Thank you guys!
     
  2. jcsd
  3. Jan 30, 2015 #2
    I don't believe that would be a good comparison. Unfortunately, this is the most troubling aspect of CFD: model validation.
     
  4. Jan 30, 2015 #3
    A water jet in air will behave different from a water jet in water. An air jet in stagnant air will behave in the same way as a water jet in stagnant water. This means you can compare measurements of an air jet (in air) with a water jet (in water) after scaling the results properly. There must be hundreds of papers describing measurements and simulations of round and planar jet flows. The constants appearing in turbulence models were derived from such measurements! And you will quickly discover that even for such simple cases, some turbulence models will completely fail to predict even the most basic properties of such jets, like the spreading rate.

    The best paper on measurements in turbulent round jets is
    Hussein,Cap,George, Velocity measurements in a high-Reynolds-number, momentum conserving,axisymmetric, turbulent jet, Journal of Fluid Mechanics 258 (1994) pp. 31-75
    As soon as you ignite your jet, you have to use measurements done in a reacting flow, off course.
     
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