ORIGINAL RESEARCH article
Front. Energy Res.
Sec. Wind Energy
Volume 13 - 2025 | doi: 10.3389/fenrg.2025.1593940
This article is part of the Research TopicCo-operative Progress in Distributed Wind and Hydrokinetic Energy SystemsView all 5 articles
On the outer boundary conditions for the fluid dynamics simulation of vertical-axis turbines
Provisionally accepted
David Howe Wood*
Narges Golmirzaee- University of Calgary, Calgary, Canada
Select one of your emails
You have multiple emails registered with Frontiers:
Notify me on publication
Please enter your email address:
If you already have an account, please login
You don't have a Frontiers account ? You can register here
Many computational fluid dynamics simulations of isolated vertical-axis turbines use a 2D, rectangular computational domain and slip or symmetry boundary conditions (BCs) along the domain's lateral outer boundaries or side walls. These BCs prevent any flux of mass and momentum across the side walls, and so can cause the velocity at the domain inlet to be less than the freestream velocity at infinity. Making the further simplification that the flow is steady, an equation for the difference between these velocities is derived from the impulse form of the axial momentum equation for a control volume that coincides with the outer boundaries. The difference depends on the turbine thrust and the distance to the side walls. Corrections are derived for the power and thrust coefficients for isolated turbines and estimates provided for the domain size needed to reduce the correction to a specified level. When multiple turbines are arranged normal to the flow in close proximity, symmetry or periodic BCs are appropriate but the difference between the inlet and freestream velocity can be large enough to invalidate recent claims that proximity increases the power output. We argue that both isolated and multiple turbine simulations should use BCs that include a point vortex for consistency with the turbine side force and a point source for consistency with the thrust. Nevertheless, it is not possible to ensure consistency with the moment equation for the control volume and this may affect the accuracy of the calculated power output.
Keywords: computational fluid dynamics, Boundary conditions, Vertical axis turbines, Impulse equations, Blockage
Received: 14 Mar 2025; Accepted: 10 Jun 2025.
Copyright: © 2025 Wood and Golmirzaee. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: David Howe Wood, University of Calgary, Calgary, Canada
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.