Interesting article by TotalSim on the modelling of loaded tyres in computational fluid dynamics (CFD) simulations.

It’s important to bear in mind that the round tyre we think of as being attached to the four corners of our vehicle (or the front and rear of our motorbike) is anything but round in reality.

To quote Jan Prins, technical specialist at Jaguar Land Rover (as he is quoted by Blundell and Harty, 2015);

“When people say that tyres are round and black, I tell them they have the black bit right. Mostly”

Tyre deformation occurs under any form of load – perhaps the most basic example to consider is a vehicle sitting stationary on a flat patch of tarmac – even then the tyre is not perfectly round. It forms a contact patch with the road as it deforms at the base of the tyre.

Clearly, the situation becomes more complicated as additional forces are placed upon the vehicle during a dynamic, moving situation. This coming before we even consider whether the tyre itself is inflated to the correct pressure.

Sounds more like we’re looking at the vehicle dynamics rather than the aerodynamics so far, right?! You might think so – but the shape of the tyre, the movement of the vehicle under load and the dynamics of the vehicle has a huge impact on the aerodynamics – just as the mass of the vehicle, engine specification and placement do. All these various aspects of the vehicle are linked and connected.

So check out their article and consider how that might effect the simulation results.

Reference: Blundell, M and Harty, D (2015); The Multibody Systems Approach to Vehicle Dynamics: Second Edition. Butterworth-Heinemann, Oxford.