Experimental study on Ahmed's body drag coefficient for different yaw angles

Abstract We present experiments conducted in a wind tunnel to characterize yaw angle effects on the drag force acting on the Ahmed body with slant angle of 25°. The main contribution of this experimental work is to create a reliable database of drag coefficients under yawed conditions. For zero yaw angle, we find a small variation in the drag coefficient, CD, for Reynolds number in the range 3 × 10 5 − 30 × 10 5 , resulting in the known tendency of a drag coefficient decrement as the Reynolds number increases. This trend is in agreement with other experimental works but is 30% greater than the usual CD (Re) function. Secondly, the drag coefficient increases significantly with an increment in the yaw angle at a constant Reynolds number. Three distinctive regions for the drag coefficient as a function of the yaw angles are established from the experimental results: the drag coefficient increases for 0 ° ≲ β ≲ 60 ° , remains constant in the range 60 ° ≲ β ≲ 75 ° and finally, the drag coefficient grows again until β = 90 ° .

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