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-   -   Venturi Modelling Pressure Changes Seem Too Low (http://www.cfd-online.com/Forums/fluent/99615-venturi-modelling-pressure-changes-seem-too-low.html)

Patrick H April 7, 2012 17:06

Venturi Modelling Pressure Changes Seem Too Low
 
Hello,

I am currently trying to model the flow through a long-form venturi with a beta ratio of about 0.75 and inlet diameter of 0.0525018 m (2.067 in). I have constructed the mesh to replicate an experimental setup, the results of which I will later compare with the results of my CFD model. I am using the standard k-e model with standard wall treatment. Inlet boundary type is mass flow (6 kg/s and 220000 Pa) and outlet is a outflow boundary (flow weight ratio of 1). So far my result look good; clear differential pressure generation and pressure recovery in the divergence cone. However when I plot the pressure distribution my pressure values start at zero and go to about -12 with the units being in Pa. This pressure drop seems far to small and I would prefer if the pressure were displayed in their actual value rather than a negative. Can anyone explain why I am seeing such an unrealistically low pressure drop?

Please let me know if there is any additional information I can supply which would be helpful in determining my problem.

whiz April 27, 2012 03:11

This is because you set the reference as 1 atm. RIght?
Quote:

Originally Posted by Patrick H (Post 353645)
Hello,

I am currently trying to model the flow through a long-form venturi with a beta ratio of about 0.75 and inlet diameter of 0.0525018 m (2.067 in). I have constructed the mesh to replicate an experimental setup, the results of which I will later compare with the results of my CFD model. I am using the standard k-e model with standard wall treatment. Inlet boundary type is mass flow (6 kg/s and 220000 Pa) and outlet is a outflow boundary (flow weight ratio of 1). So far my result look good; clear differential pressure generation and pressure recovery in the divergence cone. However when I plot the pressure distribution my pressure values start at zero and go to about -12 with the units being in Pa. This pressure drop seems far to small and I would prefer if the pressure were displayed in their actual value rather than a negative. Can anyone explain why I am seeing such an unrealistically low pressure drop?

Please let me know if there is any additional information I can supply which would be helpful in determining my problem.



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