An analysis tool for planes and sails operating at low Reynolds numbers

flow5 is a potential flow solver with built-in pre- and post processing functionalities. Its purpose is to make preliminary designs of wings, planes and sails both fast and user-friendly.

Potential flow solver

To solve the potential flow problem, flow5 includes the following methods already implemented in xflr5:
– A non-linear Lifting-Line Theory methods which follows the methodology described in the report NACA-1269
– Two VLM methods using quad ring vortices and horseshoe vortices.
– A volume quad panel method based on the report NASA 4023

In addition, two triangular panel methods based on Galerkin formulations have been included in flow5. The first uses uniform source and doublet densities on panels, the second uses uniform source and linear doublet densities. The benefit of triangular methods is their ability to describe general 3d surfaces. In addition, the linear method improves the accuracy of the predictions in cases of high local pressure gradients.

In the case of plane analyses, the inclusion of viscous drag is made available by interpolation of 2d airfoil viscous data generated by the XFoil program. However, since XFoil is not part of flow5, the program uses xflr5 as an external back-end to generate the 2d viscous data.
The evaluation of viscous drag is not included in the boat analysis module.


flow5 includes the core capabilities of xflr5 for plane analyses, and of sail7 for boat analyses. A number of new features have been introduced to improve on these two applications and to make the analyses more user-friendly, versatile and accurate.
User Interface (UI)
3d Galerkin formulations
Plane analyses with fuselage
Non linear control polars
Intel MKL
CAD Interfaces
2d Interactive Boundary Layer solver

Alpha and beta phases, and first version

The alpha phase was closed on November 15th, 2019.
The beta phase was due to last until end of June 2020, but has been extended by 3 months to allow time for validation and benchmarking.
The first version 7.1 of flow5 will be released at the end of the beta phase. Since the goal is to target stability of this first version, all major new features will only be implemented in later versions of the application.


flow5 is available under a commercial licence on a subscription basis. The intent of the commercial license is to provide support to the on-going development.
For beta-backers, subscriptions are available for the duration of the beta phase + 1 year of use.
On the long term, nothing is firm, but the intent is that flow5’s price remains affordable for students and private individuals.


flow5 has been designed to run on all configurations which support xflr5.
Performance scales with the power, speed, and number of cores of the processor.
Check-out the detailed hardware requirements before purchasing flow5.

Bug reports and feature requests

Until a ticket functionality similar to the one available for xflr5 is added to this website, please use the discussion section to report a bug or request a feature.
Check out also the troubleshooting section to fix the most common issues.


xflr5: xflr5 is an analysis tool for airfoils, wings and planes operating at low Reynolds Numbers
sail7: sail7 is a tool designed for the analysis of sail boat performance
XFoil : XFoil is an interactive program for the design and analysis of subsonic isolated airfoils

Video tutorials

flow5 – video tutorials

Documentation and resources

A tentative online documentation is under construction, focusing first on user questions and comments, and on the most recently introduced features..
The presentation documents and project files used in the demonstration videos can be downloaded from this page.


flow5 ® is a registered trademark in France of the company Cère-Aéro.