Little league baseball season has already started and once again I’ve found myself stuck for hours on the bleachers of some school baseball field. This year I have two baseball players, now that Master Andrew has decided he’s got game and joined the Shetland division. That’s a long time on the bleachers!  To try and do something useful with all that time, rather than listening on the latest gossip of the coach’s extra-marital affair, I took with me some of the notes and papers I collected during SolidWorks World. There was this very interesting session I attended, and I don’t think I have even mentioned it here yet. This is one of those that felt way beyond my reach for now, but interesting and inspiring, just the same. It was about the redesign of a land speed vehicle using CFD with Simulation Flow, or as it was previously known, COSMOS FloWorks. The presenter was David C. Woodruff, from Design Dreams, LLC.  This vehicle was also known as the Project BUB, but, as far as I understand, should not be confused with this  other BUB that was featured at the Partner Pavilion; the BUB Seven, which is actually a motorcycle. Yeah, well, the first motorcycle to break 350 mph, anyway.

Same as BUB Seven, this other BUB was a vehicle designed for speed, and its final performance was to be put to the test at the Utah Salt Flats, only its not a motorcycle.

 I’m not exactly familiar with this place. I’ve never been to the Salt Flats, but according to a selected group of enthusiasts that have devoted a great deal of their time and money designing vehicles for this venue,  a very low Drag co-efficient (Cd) is required, as well as enough down force for traction and stability.  These two requisites are not easy to accomplish; small changes in the structure of the car can have a big impact. In the past, optimizing a design for such a vehicle required repeated trial and error running multiple experimental prototypes and making changes based on the result of these run tests. Nowadays, CFD is the way to go.

With the aid of 3DVision and using SolidWorks Simulation Flow, the vehicle was redesigned from what it was originally in 2007 ( a vehicle that resembled the JCB diesel LSR ) to a much more aerodynamic vehicle that is just being finished and should be ready for its first run at the Bonneville Salt Flats in August 2009. According to David Woodruff, who is the team’s aero guy, Simulation Flow was not only easy to learn, but provided accurate results when compared to both, experimental tests and results obtained with high end systems. He also praised its meshing capabilities, because they allowed him multiple possibilities for tweaking the mesh and achieving the desired mesh density in just the right areas.

Using Simulation Flow, David was able to create a virtual wind tunnel, and track important data such as lift, down force, drag, torque, surface pressures and surface velocities.  Doing this allowed David to obtain information that he wouldn’t normally obtain from a real-life wind tunnel.

The following images show the changes in the vehicle from 2007 to 2009. In 2007, the Cd was 0.208 with a down force of 289 lb, and a total horsepower required of 1420 HP.  In the image you can also observe the large turbulences underneath the vehicle, which makes placing a parachute unsafe.

The new re-designed vehicle included an inverted aerofoil, and it shows in this image a smoother plot in the rear and less turbulence, which permits safer deployment of the parachutes.  In the current vehicle (2009) Cd is 0.134, with a down force of 106 lbs and horsepower of 1233 HP.

Like I mentioned before, this vehicle is currently being prepared and should be running at the Salt Flats in August this year. If you have some time and you are into speed, perhaps you should consider dropping by to watch the races at the Bonneville Speed Week.  Not your average car or motorcycle race, that’s for sure!