Analysis of the Sweeped Actuator Line Method

Matthew Churchfield, Jorn Nathan, Christian Masson, Louis Dufresne

Research output: Contribution to journalArticlepeer-review

5 Scopus Citations


The actuator line method made it possible to describe the near wake of a wind turbine more accurately than with the actuator disk method. Whereas the actuator line generates the helicoidal vortex system shed from the tip blades, the actuator disk method sheds a vortex sheet from the edge of the rotor plane. But with the actuator line come also temporal and spatial constraints, such as the need for a much smaller time step than with actuator disk. While the latter one only has to obey the Courant-Friedrichs-Lewy condition, the former one is also restricted by the grid resolution and the rotor tip-speed. Additionally the spatial resolution has to be finer for the actuator line than with the actuator disk, for well resolving the tip vortices. Therefore this work is dedicated to examining a method in between of actuator line and actuator disk, which is able to model the transient behaviour, such as the rotating blades, but which also relaxes the temporal constraint. Therefore a larger time-step is used and the blade forces are swept over a certain area. The main focus of this article is on the aspect of the blade tip vortex generation in comparison with the standard actuator line and actuator disk.

Original languageAmerican English
Article numberArticle No. 01001
Number of pages8
JournalE3S Web of Conferences
StatePublished - 16 Oct 2015
Event2nd Symposium on OpenFOAM in Wind Energy, SOWE 2014 - Boulder, United States
Duration: 19 May 201521 May 2015

Bibliographical note

Publisher Copyright:
© 2015 Owned by the authors, published by EDP Sciences.

NREL Publication Number

  • NREL/JA-5000-68400


  • actuator line method
  • blade tip vortex generation
  • wind turbines


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