We successfully ran a 18.2 million cell CFD case on our newest GT model, which includes the engine, gearbox, differential, shafts etc. This is the closest detail level to a production car we will be running CFD calculations on.

The finer mesh seems to have improved the quality of the results since the calculation converged much sooner with the finer mesh.

Downforce: 5431N

Drag: 1101.8N

We are satisfied with the numbers the last aero kit produced and are now focusing on creating a production capable model.
None of our previous aero kits included the engine/gearbox/drivetrain, we added these to the last kit and it dramatically reduced the downforce value to around 4000N. However, we can sacrifice the weight distribution a bit to gain some(most) of the lost downforce. This is partly possible due to the small 1l engine we will be using which allows us to place it quite freely.

We adjusted the new model slightly. The new diffuser design produces massive values in the CFD calculations. With a design that is based on a stock car we have a considerably better downforce/drag-ratio than the group C Le-mans prototypes before the rule changes. The Nissan P35 at best achieved a downforce/drag-ratio of 5.36. Our most recent value is 5.69.

As for how realistic our CFD values are, we won't really know until we are able to take the car to the track.

Downforce: 6303N

Drag: 1107N

  • gt_newdif

We had a great idea and completely redid the diffuser. The new diffuser produced a much larger low-pressure area than before and thus produced much more downforce than any of the previous versions. We can likely further improve the model with a few small changes so we will continue the development.

New values:

Downforce: 5714N

Drag: 1056N

We tried an even more extreme-sized diffuser, which again increased the downforce, but only by a very small amount.

There is something strange going on in the model. We will have to analyze the flow field and model carefully. The opening angle and the area ratios of the diffuser seem to be much larger than should be possible based on public knowledge. The flow "should" separate from the surface of the diffuser at much smaller values so it's a bit unclear how good our aero kit actually is. We are especially going to investigate the mesh and turbulence parameters.

Downforce: 4300N

Drag: 1017N

  • opel-gt-13-900

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