The car has a fuel level sensor (FLS) to check the amount of fuel remaining. FLS is a structure in which the height of float varies with the amount of fuel. Fluid behavior can be found in CFD software simulations such as Particleworks. However, CFD is not enough to know the movement of an object that changes due to fluid. This is because we have to solve the equation of motion further. Solving the equations of motion is specialized in Multi-Body Dyanmics (MBD) software like RecurDyn. Therefore, if you use CFD and MBD software in FLS simulation, you can analyze the FLS system which changes according to the amount of fuel.