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Influence Of Thermal Stability On CFD Simulations Catherine Meissner David Weir Arne R. Gravdahl

Influence Of Thermal Stability On CFD Simulations Catherine Meissner David Weir Arne R. Gravdahl. Stratification of the atmosphere. First influence of temperature on the wind field: change of the wind speed profile. Neutral case. wind speed. height. Non-neutral case.

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Influence Of Thermal Stability On CFD Simulations Catherine Meissner David Weir Arne R. Gravdahl

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  1. Influence Of Thermal Stability On CFD SimulationsCatherine MeissnerDavid WeirArne R. Gravdahl

  2. Stratification of the atmosphere First influence of temperature on the wind field: change of the wind speed profile Neutral case wind speed height Non-neutralcase

  3. Stratification of the atmosphere Second influence of temperature on the wind field: buoyancy force The flow is prevented to pass over the idge under stable conditions Stable Assuming neutral conditions when it is stable conditions gives too high wind over ridge Neutral Needs transient simulations Unstable

  4. Temperature, momentum and turbulence Temperature influence on velocity by the Boussinesq approximation deviation from the reference temperature Temperature influence on turbulent kinetic energy and dissipation considered by additional terms in the turbulence closure

  5. Simulation for a cosine hill Cosine hill: height = 200 m, length = 800 m, wind from west Neutral Stable V y y x x z U x z Neutral conditions gives a higher speed at hilltop m/s 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 x

  6. Evaluation for Hundhammerfjellet Wind speed measurements for 30, 73 and 83 m height, and temperature measurements for 50 and 83 m are available for the period from April 2006 to January 2007

  7. Evaluation for Hundhammerfjellet Sector: 240 Sector: 300 Sector: 150 Sector: 150 Sector: 180 Sector: 0

  8. Evaluation for a forested site and complex site Wind speed measurements for 30, 48, 80 and 100 m height, and temperature measurements for 5 and 97 m are available Wind speed measurements for 10, 30 and 35 m height, and temperature measurements for 6.5 and 45 m are available Visit our poster for more details

  9. Stratification another tuning option! What do to when the simulations doesn’t fit the measurements? Historically elevation and roughness has been adjusted to compensate for incomplete modelling Can we define proper stability models capable of reproducing reality? Or will stability become another tuning option?

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