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matching pressure drop with test set up

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Old   November 13, 2012, 23:43
Default matching pressure drop with test set up
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I'm running a simulation that has a lower pressure drop than what I'm reading from a similar experimental test set up. In the test set up, there is a fan at the inlet whereas in the simulation the inlet is just velocity with uniform flow. I'm guessing the higher losses in the experiment are due to fan swirl, because all the dimensions between the two are exact. How do I account for the extra DP in the experimental set up caused by the fan? I have tried messing with the turbulence intensity and other settings but that had zero influence.
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Old   November 14, 2012, 05:01
allan thomson
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You can use a porous region close to the exit of the domain and successively reduce the pososity until you get the desired pressure drop between the inlet and outlet.
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Old   November 15, 2012, 20:13
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It's also a matter of how much your simulation results differ from the experimental ones. Many people either overestimate the accuracy of simulations or underestimate the effort needed to produce "exact" results.

Also, don't bother too much with comparing experimental results with simulation results unless you REALLY know what's going on in the experiment. I've seen too many people bothering about the difference between simulation and experiment - but they didn't even know the limitations of the experiment and how big the experimental error was (and believe me, experiments can be as wrong as simulations).

Nobody trusts a simulation - except the guy who did it.
Everybody trusts an experiment - except the guy who did it.

Of course, that doesn't necessarily mean your simulation is right - just try to simulate exactly what you've been measuring.
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