CFD software reveals the secrets of flight

A Mentor Graphics Mechanical Analysis Division product story

Edited by the Engineeringtalk editorial team May 26, 2008

YouTube video combines actual footage of human flight in wingsuits with airflow simulations using computational fluid dynamics software.

Flomerics and Matchstick Productions have produced a short video that for the first time reveals the complex 3D airflow around a wingsuit that enables human beings to glide through the air like a bird.

The video combines actual footage of human flight in wingsuits with airflow simulations using computational fluid dynamics (CFD) software.

The actual wingsuit flight segments come from the film "Seven sunny days" by Matchstick Productions.

Flomerics' EFD family of computational fluid dynamics (CFD) software was used to calculate the fluid flows and pressures that produce lift and drag forces that enable wingsuit fliers to glide with an extraordinary level of control that enables them to trace the contours of rock ledges and other obstacles from just a few feet away.

The wingsuit flier enters a freefall wearing both a wingsuit and a parachute.

When exiting from a base jumping site or a helicopter, the flier begins with a vertical drop to use the forces of gravity to accelerate to a speed that the wingsuit can then use to produce lift.

Wingsuit fliers typically fly at speeds of about 95km/h.

The wingsuit flier manipulates the shape of their body to balance the aerodynamic forces and create the desired amount of lift and drag.

The hands act as ailerons and very small hand movements control pitch and roll movements.

An experienced flier can demonstrate amazing maneuverability by arching or bending at shoulders, hips and knees or changing the shape of their torso.

The wingsuit flier finally lands by deploying their parachute.

Flomerics' EFD software made it possible to use 3D computer aided design (CAD) geometry directly to represent the human body.

Flomerics engineers added thin shell elements between the arms and torso and between the legs to create a model of a human wearing a wingsuit.

The rotation of key body joints such as wrists, knees, elbows was specified and changed easily within the solid model.

Then they attached boundary conditions to the model such as giving the body a forward velocity of 95km/h.

All ancillary data required for flow simulation, such as material properties and boundary conditions were associatively linked to the CAD model and carried along with all design changes.

The software analysed the CAD model and automatically identified fluid and solid regions without user interaction.

Then the automatic mesher created the mesh while maintaining an exceptionally high level of quality, eliminating the need for any manual intervention.

The ability to use the 3D CAD model directly was a key advantage in this analysis because of the need to model different arm, leg and hand positions in order to understand the extraordinary maneuverability of wingsuit fliers.

The engineers performing the analysis simply changed the angles of various body joints in the CAD model.

Then in a few minutes they were able to mesh the new models and perform CFD analysis in much less time than would be required using conventional CFD methods.

Although many engineers still think of CFD software as being difficult, time-consuming and expensive to use, this application demonstrates that a new generation of CFD software has addressed all these concerns.

EFD's ability to integrate CFD into the design process allows design engineers to focus on the physics of the problem, which in most cases they already understand well, and generate results much more quickly.

This makes it possible for design engineers to get reliable answers, gain insight, and deliver tangible results that lead to improvements in product performance, lower costs and reductions in time to market.

The video is posted on YouTube, and can be accessed via a link on the Flomerics website.