Computational Fluid Dynamics (CFD) service specifically designed for the bicycle industry. www.velocite-bikes.com

1. Velocite
Aerodynamics
Consulting
CFD Simulations and Design

2. Examples of aerodynamic design
Aero Not aero

3. Why consider aerodynamics?
Functional benefits
● reduced drag
● improved handling
● improved brake cooling
Business benefits
● better marketing story
● more OEM wins
● unified design language
○ reduced tooling costs
○ reduced part count
● create unique products

4. What do we do?
● Use computational fluid dynamics (CFD) to
simulate external airflow over an object
○ Bike, brake, wheel, handlebars, fork, etc.
● Give advice and guidance on aerodynamic
design
○ Is your design aero? We can make it so.
● Provide aerodynamic designs
○ Do you need a new aero product? We can design it.

5. Computational Fluid Dynamics (CFD)
What is CFD?
● in aerodynamics, CFD delivers visual and
numerical analysis of airflow around the
object
● Unlike wind tunnel studies, CFD allows
visualization of airflow and makes rational
aerodynamic design possible

6. CFD versus wind tunnel
CFD
● visualization of airflow
● used for design and
development
● results not dependant on
external conditions
● in Velocite’s case, results also
not dependant on problem or
operator
● good for marketing in the bicycle
industry
● more expensive
Wind tunnel
● used for verification of
assumptions or design, not for
development
● results depend on operator,
experiment setup, day to day
conditions, wind tunnel setup
● faster results
● great for marketing in bicycle
industry
● cheaper (as used by the bicycle
industry)

7. Who uses CFD?
Since the 1970’s everyone in aerospace
industry relies on CFD for primary design and
development

8. Velocite CFD versus others
Velocite
● Lattice-Boltzmann with
LES turbulence model
● transient flow
simulations
Complex, computationally
much more demanding.
Not possible to run on a
workstation.
Other
● Navier-Stokes with K-ε
→ DES models
● generally steady state
simulations
Much simpler and
computationally less
demanding. Workstation
level.

9. Examples
Lattice-Boltzmann LES, transient.
Velocite standard
Navier-Stokes K-ε, steady state.
Industry standard

10. Example Airflow detail: front brake location
Rotating wheel simulation: 42 km/h @ 12 degrees angle of attack. 132 million
cells, 20 thousand time steps.
Front view Rear view

11. Example Airflow detail: short conclusion
● Layer of air adheres to the surface of the wheel and has direction vector
that follows the rotational vector of the wheel
● Bulk airflow vector is aligned with the apparent wind direction
● High air pressure is observed on the front faces of the fork - this is
especially significant at yaw
Conclusion: brake shape and mounting location
or integration impacts the overall bicycle
aerodynamics

12. More examples: Velocite YouTube channel
● Three spoke wheel simulation
○ http://youtu.be/Qb9VkYOdCBw
● Airflow around water bottles:
○ http://youtu.be/g08s7hR70ok
● Velocite RT50 wheels
○ http://youtu.be/mGGm1gEJd8U
● Ahmed body validation example
○ http://youtu.be/2I0t5FHKHYc

13. How accurate or reliable is our CFD?
● We use custom made software developed for Velocite by a team of
scientists at The University of Geneva, Switzerland
● Velocite CFD expertise was developed through our past and current work
with:
○ Acer Computers
○ NARL NCHC (National Center for High Performance Computing)
division
○ NCKU (National Cheng Kung University) in Tainan

14. Advantages of Velocite method
● Much higher resolution
○ allows better design decisions
● More realistic results
○ not idealized, nothing is hidden or smoothed over
● Correctly simulates downstream airflow
○ can determine how design changes impact the rest
of the bicycle
● Can use actual physical 3D model
○ no separate meshing or preparation step

15. How can our service benefit you?
We can help you design your new world
class aero product
If you already have a product, but no data we
can help you validate your design
We can make the all-important CFD
simulation images, videos and data
Design
Validation
Marketing

16. Velocite CFD offer
● Simulate 3D airflow around any number of parts,
including rotating wheels, or cranks
○ variable airspeed, variable angle of attack, variable rotational, or
periodic velocity, as required
○ Simulation runs on our in-house compute cluster in Taiwan
● Provide detailed aerodynamics analysis and design
recommendations, numerical data, images and videos
as required
● Competitive pricing that can suit any design and
development budget