Question

5. Flow over a Bod;y (a) The drag coefficient for a smooth sphere is shown in the figure below. Determine the speed at the critical Re for a 42 mm diameter sphere in air. (This is a golf ball sized object.) You may assume air at 60°F. 0.5 0.4 0.3 0.2 0.1 4 105 Re-Du/v 103 106 107 (b) Ģolthal, "dimples" cause the drag drop to occur at a lower Reynolds number. The table below gives the drag coefficient for a rough sphere as a function of the Reynolds number. Plot the drag for a 1.65 inch diameter sphere as a function of velocity. Assume air at 60°F TABLE FOR GOLF BALL 7.5 0.48 10 0.38 20 0.12 25 0.10 Re x 10 15 0.22 (c) Graph the results of Problem (a) and (b) on the same graph and in one sentence describe what the data describes.

could you please make clear answer?

Answer 1

5 (c。Determine -the speed at the critica Re for a 42mm diameter Sphere în air. Sot Diameter ơt the sphere is D -42mm Kinematic wscosity is fluid density is ρ fluid viscoSIN is μ Phiical properties gases and liguids fer alr al 2o Critical Reynolds number , Re ^ 2x l From e^n (2x lo5) (42mm) ( 15-11 xaf ㎡/s) (2ns) (o-o42 m) V 11.95 mlS The Speed at the critical Re Por a 42mm diameter sphere în arts ㄱ1.95m/s