The Standalone DWM model is a high-fidelity engineering wake model which allows for transient wake simulations of large wind farms in a time effective manner. The model incorporates the effect of oncoming wind speed, atmospheric turbulence, wake generated turbulence, atmospheric stability and turbine characteristics in the calculations. The output of the model is time series of wind speed and turbulence at each turbine location in the analysed wind farm. This allows for a consistent calculation of wake effect on power production and turbine loads.

**The key benefits compared to other engineering wake models used in the industry:**

- The Standalone DWM model can simulate both the mean velocity and the turbulence field downstream of a wake-emitting turbine. This eliminates the need for separate models for yield and turbulence as is the current industry practice in wind farm design calculations.
- Standalone DWM has the capability to include all relevant ambient flow properties as well as the turbine induced effect on the flow field inside the wind farm (e.g. the build-up of small-scale turbulence along a row of turbines or the reduced wake recovery inside a large wind farm)
- The model is designed to use time series of flow properties as input. Wake calculations based on transient physics have the advantage of implicitly capturing the correlation between the aforementioned flow properties (eg. correlation between shear, turbulence and wind speed), but even more important it captures the response of the wind farm based on distributions rather than average quantities.
- The Standalone DWM model captures the effect of large and small turbulent length scales. As some turbine loads are driven by large scale wake dynamics, it is not sufficient to describe the wake as long term averages of wind speed and turbulence intensity. Instead, the random large scale movements of the wake need to be taken into consideration to capture the dynamic effects. This ability is implicitly built-in to the standalone DWM model, making it a prominent simulation tool for first order screening of turbine loads

The Standalone DWM is a further development of the standard dynamic wake meandering (DWM) model. The standard DWM model is designed to be coupled with an aero-elastic solver for calculation of component loads of wake-affected wind turbines, and is currently being included in the IEC 61400-1 standard for wake load calculations. The underlying physics of the two models are similar, the main difference is that the Standalone DWM model is driven by a pre-calculated database to facilitate high speed calculations. More information about the DWM model and the Standalone implementation can be found in our methodology section.

#### References

- Keck, R‐E. (2013), PhD Thesis, A consistent turbulence formulation for the dynamic wake meandering model in the atmospheric boundary layer. Freely available for download at: http://orbit.dtu.dk/en/publications/a-consistent-turbulence-formulation-for-the-dynamic-wake-meandering-model-in-the-atmospheric-boundary-layer%280222ac75-fd0b-42e0-9345-aa3dc493bd71%29.html
- Keck R‐E., de Maré M., Churchfield M. J., Lee S., Larsen G. and Aagaard Madsen H. (2014), On atmospheric stability in the dynamic wake meandering model,
*Wind Energ.*, 17, pages 1689–1710, doi: 10.1002/we.1662 - Keck R‐E., de Maré M., Churchfield M. J., Lee S., Larsen G., and Madsen H. A. (2015), Two improvements to the dynamic wake meandering model: including the effects of atmospheric shear on wake turbulence and incorporating turbulence build‐up in a row of wind turbines,
*Wind Energ.*, 18, pages 111–132. doi: 10.1002/we.1686 - Keck, R‐E. (2015) Validation of the Standalone implementation of the dynamic wake meandering model for power production.
*Wind Energ.*, 18: 1579–1591. doi: 10.1002/we.1777 - Keck, R‐E., and Undheim, O. (2015) A pragmatic approach to wind farm simulations using the dynamic wake meandering model.
*Wind Energ.*, 18: 1671–1682. doi: 10.1002/we.1783