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Prediction of the critical Reynolds number

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Old   May 13, 2014, 11:45
Arrow Prediction of the critical Reynolds number
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Mehrez
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Hi every one,
I'm using OpenFoam for simulating fluid flow in periodic media.
Do you have an idea on how can I predict the laminar/turbulent transitional Reynolds ?
Thank you in advance

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Old   May 15, 2014, 01:36
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Karl-Johan Nogenmyr
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Well, in theory it should be possible using a DNS solver and sweep the Re-number, while assuring there is some small disturbances present. If you are below the critical number, the disturbance should decay, while if you are above, it should grow (into turbulence).

In practise it is tricky because you need to assure that your numerical viscosity is small enough (to be accurate in Re), and things like wall roughness may play significant role.

For an academic case (smooth wall), this is possible with OpenFOAM, (dnsFoam solver), but you would need massive computational resources (i.e. hyper-fine mesh)

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Old   May 15, 2014, 11:21
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Hi dear Kalle,

Thank you for your answer.
Concerning my geometry, I have smooth walls. I have proceeded like you said by DNS (using IcoFoam solver with dimensionless NS equations).
I have got results but I want to verify if it is OK. I thought about the linear stability theory but OpenFoam doesn't have a such solver, so to validate my DNS results I need to adopt another method...
Best regards,

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laminar/turbulent, reynolds, transition, unsteady

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