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-   -   Pressure and molecular weight ? (http://www.cfd-online.com/Forums/fluent/50174-pressure-molecular-weight.html)

Jane January 2, 2009 05:17

Pressure and molecular weight ?
 
1. I've the problem due to the pressure in the mold.

i create a point at the desire location (according to experiment setting) to function as a pressure transducer in mold filling model. I use vertex average as a type for this point and monitor it as Static Pressure.

what i not understand is, the monitoring results show the constant pressure when the plastic filled the mold. But in the experiment, the pressure was drop after achieve highest pressure.

i also tried another type such as Facet average, it's also give me the constant pressure at the end of filling.

Anyone have suggestion about this situation?

2. Question about Molecular weight and Standard State Enthalpy data that require in FLUENT.

Because of the setting requirement in FLUENT in this mold filling case, Molecular weight and standard state enthalpy are require to fill in the material panel for plastic material.

In the simulation, i found FLUENT does not use both parameters during analysis. It is because when i apply lowest and highest value for both parameters, the plastic flow front in the mold seem not affected by both parameters.

theoretically, for polymer cases, when the molecular weight is higher, the flow front should become slower than plastic that have lowest molecular weight .

This make me headache with both problem in mold filing simulation.

Anyone please give me suggestion about both cases above. Thanks.



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