Development of a data assimilation method using vibration equation for Large-Eddy Simulations of turbulent boundary layer flows

Nakayama, Hiromasa   ; Takemi, Tetsuya*

We proposed a data assimilation method using a vibration equation which can incorporate turbulence winds toward target mean winds while maintaining small-scale turbulent fluctuations. First, we conducted test simulations in which nudging is applied in a basic turbulent boundary layer (TBL) flow toward a target one. It was shown that the basic TBL flow can be reasonably nudged toward the target one while maintaining the turbulent fluctuations well, when prescribing the natural frequency in the vibration equation smaller than the spectral peak frequency in the TBL flow. Then, we applied the proposed nudging method by incorporating data obtained from meteorological observations located in the southern part of the actual city of Kyoto. The mean wind velocity profiles are reasonably nudged toward the target observed profile and the turbulence statistics are also favourably maintained. It is concluded that the LES data assimilation method successfully nudges toward the turbulence winds well.