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Log law for unsteady velocity profile

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Old   July 11, 2012, 07:47
Default Log law for unsteady velocity profile
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hayder
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Hi
I want to simulate the unsteady wind flow over a house. For steady simulation I use Log law velocity profile but I couldn`t find a formula for the Unsteady simulation where the wind speed is changes with time. so I wonder what is the formula for such problem ?
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Old   July 11, 2012, 10:02
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Quote:
Originally Posted by hyderkhan74 View Post
Hi
I want to simulate the unsteady wind flow over a house. For steady simulation I use Log law velocity profile but I couldn`t find a formula for the Unsteady simulation where the wind speed is changes with time. so I wonder what is the formula for such problem ?

no analytical law exists for unsteady turbulent velocity, the log-law has statistical meaning for a flow in energy equilibrium (production=dissipation) such that the time derivative statistically vanishes.
If you have a flow that increases in time I suggest using LES with a grid resolving the boundary layer, however this is computational expensive.
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