A model test of a tractor-trailer rig is performed in a wind tunnel. The drag force, FD, is found to depend on frontal area, A, wind speed, V, air density, p, and air viscosity, p.. The model scale is 1:4; frontal area of the model is A = 0.625 m2. Obtain a set of
dimensionless parameters suitable to characterize the model test results. State the conditions required to obtain dynamic similarity between model and prototype flows.
When tested at wind speed V = 89.6 m/s, in standard air, the measured drag force on the model was FD = 2.46 kN. Assuming dynamic similarity, estimate the aerodynamic drag force on the full-scale vehicle at V = 22.4 m/s. Calculate the power
needed to overcome this drag force if there is no wind.