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Jonasd February 6, 2013 05:30

Virtual mass force
 
Hello, I am currently looking at calculating the force on a jet stream of water that is deflected with a known incoming flow velocity and known outgoing velocity.

If I remember correctly, this can be derived by using Newtons second law.

\bar{F} = d(m\bar{V})/dt = \dot{m}\bar{V} + m\bar{a}

Which would mean for constant velocity:

\bar{F}=\dot{m}(\bar{Vout}
-\bar{Vin})

Where \dot{m}=\rho A |\bar{Vin}|

However, i get unreasonably large forces. More likely, would be a decrease of the force with about a factor 2. Can anyone see any errors?

Thanks in advance!

Edit: My apologies for the subject line, realized that it has nothing to do with virtual mass


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