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 Temple University April 8, 2011 16:40

Pipe Contraction

We are trying to simulate a simple pipe contraction in Fluent. We have multiple cases in which we take a geometry where a length of pipe at 1 inch diameter contracts to a smaller diameter of either 1/8 in, 1/4 in, 1/2 in, or 3/4 in. We specified inlet, oulet, wall, and interior boundary conditions. Our inlet boundary condition is set to a pressure inlet at 60 psi. Our outlet boundary condition is set to a pressure outlet at atmospheric pressure. Our wall is a stationary wall with a no slip condition.

We are utilizing a k-epsilon turbulence model and are trying to measure the outlet velocity to show a trend that as the outlet diameter decreases the outlet velocity increases (as well as turbulent kinetic energy). However, as we plot the max outlet velocity from each of the contractions we are finding the opposite. The data shows that as the contraction diameter becomes smaller the outlet velocity is slower. These results do not make sense with the real world representation of this model as we have tested in the lab. Is there something we are missing here?

Is there a better way to represent this model in Fluent so that we can validate our lab results? This is my first time using Fluent...PLEASE HELP! Any additional insight would be greatly appreciated.

Thank you,
Matt

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