Vespa CFD/3D Model

Project Description

This is a project started as part of the Dry Lake Racer: CFD (Computational Fluid Dynamics) User:internetscooter scan-xpress.com.au

Source code and case settings are available at: https://github.com/internetscooter/Vespa-Labs

Information from the original CFD (Computational Fluid Dynamics) Vespa 3D Model

The data is available for registered Vespa Labs users here: Vespa 3D Model

CFD Modelling

Here is an example of what can be done with the 3D Model using open source CFD tools like OpenFOAM

add video: http://www.youtube.com/watch?v=Ykb5-e4Yd68

The above shows a test run with a "real" Vespa model but a fake rider. This shows things like the front indicators contributing a lot to the aerodynamic drag, the big red areas indicate high negative pressure zones. The above was done as a test on the VPAC MASSIVE

Research Questions

Note that the model data also includes more standard Vespa parts (rather than the race adapted version shown). Here are some research questions that would be good to answer using this data:

• 1. What is the aerodyamic drag of a Vespa?

  2. What is the lift force on the front of a Vespa at various speeds?

  3. How much does a windscreen reduce drag?

  4. What is an optimal windscreen design?

  5. What is the optimal windscreen design for reduced helmet noise?

  6. What is the drag impact of various sitting positions (regardless of windscreen)?

  7. What are the areas on a Vespa that cause the most drag and what are the solutions for reducing drag in those areas?

See also: Aerodynamic Investigation of a Scooter in the University of Perugia Wind Tunnel Facility

And review (and update as needed) Aerodynamics

What's Important

Here are some bullet points on what areas of CFD to focus on for the problem of Vespa CFD (so you don't waste effort learning stuff that is not applicable)

• incompressable flow

• bluff body

• Reynolds-averaged Navier–Stokes (RANS)

• Turbulence Models RANS based turbulent models OpenFOAM list

• Large Eddie Simulation (LES)

  • The state of the art (2013) is that CFD can predict drag +/-5%, however we need a resolution of <0.5% to do useful measurements (i.e. make small changes and say they improve Cd) - so CFD is more about predicting/analysing where problems are so that further tests can be caried out (i.e. wind tunnel or real life riding).

Additional Resources

Here are some resources that will help anyone that is learning CFD from scratch...

CFD seems to be typically taught by building on a lot of background learning, so by the time you are learning CFD at Uni you are just piecing together a number of things that you already know. If you want to learn backwards where CFD knowledge is your goal and you haven't done supporting training, then you don't know what you don't know. CFD books assume prior knowledge and won't even give a glossary of common terms that you could Google. Here is some info I have used to get some understanding. These are listed in order of required learning but you can also start at the bottom and search back up the list to find the missing bits you need as you need them.

• • Khan Academy (for when you get stuck with the math)

    • http://www.khanacademy.org/#precalculus

    • http://www.khanacademy.org/#calculus

    • http://www.khanacademy.org/#differential-equations

• Math Anxiety Relief for Nearly Everyone, W. Charles Paulsen

  • CFD Jargon: http://www.nafems.org/resources/CFDJargon/

• Mechanical - Computational Fluid Dynamics Lectures

• Aerodynamics for Students

• http://www.flow3d.com/cfd-101/cfd-101-primer.html

• http://lorenabarba.com/blog/cfd-python-12-steps-to-navier-stokes/ http://scicomp.stackexchange.com/questions/8913/beginning-computational-fluid-dynamics/

• https://scicomp.stackexchange.com/questions/19852/where-do-i-begin-learning-cfd#

Some other links that I have found along the way...

• NASA's Beginner's Guide to Aerodynamics

• http://cfdrevolutions.weebly.com/cfd-course-material.html

• http://www.innovative-cfd.com/

• http://www.engr.uky.edu/~acfd/lecturenotes1.html

• http://www.saylor.org/courses/me201/

• http://cfd.direct/openfoam/tensor-mathematics/

Books

• Aerodynamics of Road Vehicles (4th Edition): From Fluid Mechanics to Vehicle Engineering ([Proceedings] / SAE)"  - Hucho, Wolf-Heinrich.'s. table of contents

• Computational Fluid Dynamics - The Basics with Applications. John Anderson. 1995

• Essential Computational Fluid Dynamics- Oleg Zikanov a good book also i