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Long haul tractor design in the future will be challenged by freight efficiency standards and emission legislations. Along with any improvements in aerodynamics, this will also require additional cooling capacity to handle the increased heat rejection from next generation engines, waste heat recovery and exhaust gas recirculation systems. Fan engagement will also have to be minimized under highway conditions to maximize fuel economy. These seemingly contradictory requirements will require design optimization via analysis techniques capable of predicting both the aerodynamic drag and engine cooling airflow accurately. This study builds on previous work [1] using a Lattice Boltzmann based computational method on a Volvo VNL tractor trailer combination. Simulation results are compared to tests conducted at National Research Council (NRC) Canada's wind tunnel.

The importance of fuel economy and emission standards has increased rapidly with high fuel costs and new environmental regulations. This requires analysis techniques capable of designing the next generation long-haul truck to improve both fuel efficiency and cooling. In particular, it is important to have a predictive design tool to assess how exterior design changes impact aerodynamic performance. This study evaluates the use of a Lattice Boltzmann based numerical simulation and the National Research Council (NRC) Canada's wind tunnel to assess aerodynamic drag on a production Volvo VNL tractor-trailer combination. Comparisons are made between the wind tunnel and simulation to understand the influence of wind tunnel conditions on truck aerodynamic performance. The production VNL testing includes a full range of yaw angles to demonstrate the influence of cross wind on aerodynamic drag.

Underhood Thermal Management has become an important topic for the majority of automotive OEM's. To keep combustion engines cool and manage waste heat efficiently is an important part in the design of vehicles with low fuel consumption. To be able to predict cooling performance and underhood airflow with good precision within a virtual design process, it is of utmost importance to model and simulate the cooling fan efficiently and accurately, and this has turned out to be challenging. Simulating the cooling fan in a vehicle installation involves capturing complex fluid dynamic interaction between rotating blades and stationary objects in the vicinity of the fan. This interaction is a function of fan rotation rate, fan blade profile, upstream and downstream installation components. The flow is usually highly turbulent and small geometry details, like the distance between the blade tip and the fan shroud, have strong impact on the fan performance characteristics.