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The measured windscreen defrost pattern for a saloon car has been compared with two CFD simulation methods and with the results obtained using a thermal imaging camera. The objectives were to determine: if CFD could be used with confidence to simulate defrost performance; the difference between the two CFD methods; the ability of the thermal imaging technique to predict defrost performance; the most appropriate use of these techniques during an HVAC development programme. There was a good comparison between the defrost pattern on the windscreen and the results from the thermal imaging camera and the two CFD methods. The CFD methods have been shown to be suitable for fault finding and recommending their use is reinforced for development work of ducts and vents in the HVAC system. Airflow direction and distribution could be implied from the thermal camera images, which makes it a suitable tool for fine tuning duct and vent designs at the final stages of the design programme.

The airflow around an idealized wheel has been modelled using Star-CD 3.1, a commercial CFD package, and measured in a wind tunnel fitted with a moving ground. Measurements were made of the static pressure along the centreline of the idealised wheel and of the vortex characteristics immediately behind the wheel. Flow characteristics have been shown to change significantly with the introduction of wheel rotation, wheel width, and exposure to the oncoming flow. The CFD model successfully predicted the main features of the pressure profile around the wheel using the RNG k-ε turbulence model with the QUICK higher-order differencing scheme and the log-law wall function. The size of the vortex pair immediately behind the wheel and the Cp profile along the centreline of the wheel were found to be dependant upon the width of the wheel and the exposure to the oncoming flow.