# Is it wrong to associate non-isotropic flow high with Reynolds-Number and is there a better metric?

IT is often stated the flow with high Re is not isotropic, meaning there is no uniform or dominant direction of the flow. But this seems wrong to me - -while there's certainly cases where no dominant direction of flow can be discerned in highly turbulent situations, there's for example the flow through pipes or along fast moving object where there's clearly a strong anisotropy. Even an eddy in a stirred coffee cup has an easily discernible direction of flow locally.

The Reynolds number as such tells me the relation between inertial and viscous forces - is there a number or metric that tells me how non-isotropic a flow is?

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I guess you are confusing the two terms "isentropic" and "isotropic". "Isotropic" means independent from the direction whereas "isentropic" means that the entropy is constant (there are no irreversible processes going on that would increase it). – Dilaton Jan 21 '13 at 15:13
yes. I corrected this, thanks. – mart Jan 21 '13 at 15:17