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Y+ upper bound

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Old   October 2, 2012, 17:15
Default Y+ upper bound
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In relation to the k - epsilon turbulence model I infer the following from the CFX documentation:

" Y+≥11.06 and the upper limit for y+ is a function of the device Reynolds number. For example, a large ship may have a Reynolds number of 10^9 and y+ can safely go to values much greater than 1000. For lower Reynolds numbers (for example, a small pump), the entire boundary layer might only extend to around y+ = 300. In this case, a fine near wall spacing is required to ensure a sufficient number of nodes in the boundary layer. "

Could some one please explain how to check if a particular Y+ is apt for a flow with a particular Reynolds number (or) is there any way to calculate the required Y+ before starting the simulation if the Reynolds number is known
Best regards,
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Old   October 2, 2012, 19:00
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Sensitivity study - the same answer for just about any adjustable parameter in CFD.
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