Implementation of a Mixing Length Turbulence Formulation Into the Dynamic Wake Meandering Model

The work presented in this paper focuses on improving the description of wake evolution due to turbulent mixing in the dynamic wake meandering (DWM) model. From wake investigations performed with high-fidelity actuator line simulations carried out in ELLIPSYS3D , it is seen that the current DWM description, where the eddy viscosity is assumed to be constant in each cross-section of the wake, is insufficient. Instead, a two-dimensional eddy viscosity formulation is proposed to model the shear layer generated turbulence in the wake, based on the classical mixing length model. The performance of the modified DWM model is verified by comparing the mean wake velocity distribution with a set of ELLIPSYS3D actuator line calculations. The standard error (defined as the standard deviation of the difference between the mean velocity field of the DWM and the actuator line model), in the wake region extending from 3 to 12 diameters behind the rotor, is reduced by 27% by using the new eddy viscosity formulation.

[1]  J. Mann Wind field simulation , 1998 .

[2]  Torben J. Larsen,et al.  Calibration and Validation of the Dynamic Wake Meandering Model for Implementation in an Aeroelastic Code , 2010 .

[3]  J. Mann The spatial structure of neutral atmospheric surface-layer turbulence , 1994, Journal of Fluid Mechanics.

[4]  G. Larsen,et al.  Light detection and ranging measurements of wake dynamics part I: one‐dimensional scanning , 2010 .

[5]  Jens Nørkær Sørensen,et al.  Actuator Line Simulation of Wake of Wind Turbine Operating in Turbulent Inflow , 2007 .

[6]  Martin Otto Laver Hansen,et al.  Aerodynamics of Wind Turbines , 2001 .

[7]  Gunner Chr. Larsen,et al.  Wake deficit-and turbulence simulated with two models compared with inflow measurements on a 2MW turbine in wake conditions , 2008 .

[8]  Jens Nørkær Sørensen,et al.  Numerical Modeling of Wind Turbine Wakes , 2002 .

[9]  R. Mikkelsen Actuator Disc Methods Applied to Wind Turbines , 2004 .

[10]  Niels N. Sørensen,et al.  General purpose flow solver applied to flow over hills , 1995 .

[11]  Weeratunge Malalasekera,et al.  An introduction to computational fluid dynamics - the finite volume method , 2007 .

[12]  Torben J. Larsen,et al.  Wake meandering: a pragmatic approach , 2008 .

[13]  J. F. Ainslie,et al.  CALCULATING THE FLOWFIELD IN THE WAKE OF WIND TURBINES , 1988 .

[14]  N. Troldborg Actuator Line Modeling of Wind Turbine Wakes , 2009 .

[15]  Stefan Ivanell,et al.  Numerical computations of wind turbine wakes , 2007 .

[16]  S. Pope Turbulent Flows: FUNDAMENTALS , 2000 .

[17]  F. Menter Two-equation eddy-viscosity turbulence models for engineering applications , 1994 .