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Finding volumetric flow rate from pressure?

  1. Mar 9, 2015 #1
    Hello everyone,

    I am quite new to Fluid dynamics, so I would like to ask for your help.

    Is it possible to calculate volumetric flow rate from the instantaneous pressure?

    We need to know the flow rate of the air entering the cylinder in the engine due to the suction pressure. It is required to run a CFD simulation of the intake system.

  2. jcsd
  3. Mar 10, 2015 #2


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    Yes, but you need more data and some assumptions.
    You need the size of the hole the air enters by. You also need to specify whether you assume laminar air flow or turbulent.
  4. Mar 10, 2015 #3
    Thank you for you reply.

    Could you please tell me if you mean the bore of the cylinder or the intake port diameter?
    The flow will probably be turbulent, but I am not sure. Could you also give me a hint on how can I know if the flow is turbulent or not?

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  5. Mar 10, 2015 #4


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    I assume that the air enters through the intake port, so that is what is needed.
    I agree that it is probably turbulent (if the air entering the system makes a noise, it is turbulent).
  6. Mar 10, 2015 #5
    Indeed, air enters the cylinder through the intake port :)

    Thank you for giving a hint on the noise ;)

    Providing I will obtain the intake area as well as the cylinder geometry, what steps should I take then? Are there any certain formulas for that?
  7. Mar 11, 2015 #6


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    Yes, but I do not remember them (I did some work with air pressure across a small valve - 35 years ago).
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