Bloodhound SSC, simulation of desert track
 

I have just been to some inspiring events staged by the Bloodhound SSC project:
http://www.bloodhoundssc.com/. This is a project to design, build and race a 1000MPH car.
They are obviously using CFD software extensively for aerodynamic simulations.
One issue they have is that they will probably be using solid metal wheels running on a desert surface. The surface will thus deform with the wheels and with the wheels running at about 10,000RPM and the car going at 1000MPH there will be surface dynamic effects to consider.
I wondered if anyone had experience of modelling sandy soil or other ground surfaces with CFD type simulations ?