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Equations in the MRFsimpleFOAM

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Old   June 5, 2008, 01:24
Default Hi in the MRFsimpleFOAM,the
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Hi

in the MRFsimpleFOAM,the basic equation seems in the Absolute Velocity Formulation,which have the relative velocity and abolute velocity both in the momentum eqution.that is why ?is there any
advantage in that way ?
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Old   June 5, 2008, 02:15
Default Yes: you do not have to do exp
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Hrvoje Jasak
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Yes: you do not have to do explicit coordinate transformation for the MRF interface, which makes the code MUSH simpler.

Enjoy,

Hrv
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Old   June 29, 2008, 03:12
Default Hi Hrv! thank you very much!b
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Hi Hrv!
thank you very much!but i still cannot understand it very much for the question that,when you use absolut formulation,the "U" in the kepsilon model is relative velocity or absolute veloctiy?for example the production term in the k equation there is a Grad(U).what is this "U" is it relative velocity or abosolut velocity?

thanks

wayne
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Old   June 30, 2008, 03:25
Default The "relative" or "absolute" v
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The "relative" or "absolute" velocity is for the moving part of the multiple reference frames - in that region you have solid-body rotation + local flow velocity, giving you a choice of formulation.

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Old   June 30, 2008, 12:32
Default Hi Hrv! thanks!,but my equest
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Hi Hrv!
thanks!,but my equestion is when in the rotation region,what velocity is used to calculate the "k","epsilon" and "omega" for KEpsilon or KOmega turbulence model.although the equation of k","epsilon" and "omega"have the same form in the both rotation and fixed frame,they have convection term and production term which is related to the velocity,for this velocity,i think there will be different from the rotation frame to the fixed one.or i think in the rotation frame the turbulence kinetic--k is convected with the "relative velociy" and produced by the gradient of "relative velociy" ,but for the station part that is "abosulte velocity". is that right?how about the MRFsimpleFoam? could you please tell me more


thanks
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Old   May 7, 2015, 04:43
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Same doubt here.
I am using OF2.3.x and very strange results are obtained at first cell around blade. I am simulating a wind turbine.
Even if the first cell height has been calculated for a y+=100 taken into account that the blade is rotating.
pressure distribution is non-real and so epsilon field at that location. The simulation crashes quickly
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