An efficient inflow generation for large-eddy simulation of wind/tide turbine flows

Zheng-Tong Xie (AFM group, FEE)

Questions and approaches • Why turbulence?

• Why bother to use LES and to develop inflow generation method? (LES for large separation, peak loading, providing parameterisation)

• Current inflow approaches - inefficient, divergence-free not considered (e.g. inlet velocities does not satisfy continuity eq).

• Why divergence-free required? (when peak loading, acoustic issues are of interest).

• We developed a simple and efficient inflow generation –500 times faster than the old ones; artificial p flucts. significantly reduced.

• Applications: wind turbine flows, ventilation in large buildings, heat transfer at building surfaces.

Spanwise-component of vorticity at mid-span of a NACA0006 blade at α =7˚, Re =50,000 (Kim, Xie, Castro 2011)

Laminar inlet

Turbulent inlet, TI=8%

LES of flows around a static wind-turbine blade

Pressure fluctuations at x/=30

Divergence free inflow conditions for a plane channel flow

О~103 reduced!

Ref data

(Kim, Xie, Castro 2012)

Div. non-free Div. free