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marcus85 June 6, 2013 11:37

tube friction parameter with rhoSimpleFoam
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Hello cfd-online world,

my problem is to solve models, which are a really complex geometry (steady-state flow of an gasoline engine). I have to compare the results with measurements of Doppler Global velocimetry.

The Problem is that the results of the simulation are compareable with the measurements for great valve strokes, but if the stroke is lower than ca. 5 mm the differences between the measurements and the simulations are to large. Above all the pressure difference between inlet and outlet are to small in comparison to the measurements (circa 15 mbar for measured results of 50 mbar). The velocity in the valve gap are circa 120 m/s for 4 mm valve gap, so there are no sonic relations to the flow stream.

Now my question is can somebody give me an advice which parameter in which dictionary or boundary condition are compareable with the tube friction parameter lambda or the epsilon/duration ratio of the Moody-Coolebroke Diagramm?

I Have also an Problem with my convergence in this case. For this i have the boundary conditions and my fvSchemes and fvSolution file uploaded. Perhaps somebody can say me also an solution for this problem.

At first many thx for this people, who have already read my thread and even more thx for the people, who can give me good advices=)


marcus85 June 10, 2013 09:10

Nobody an Idea? If somebody have questions to me that may be helpful to answer these question, please ask me...


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