Amin Ghasemian - Senior Mechanical Engineer, Takestan Branch, Islamic Azad University,Qazvin, Iran
Mohsen Goodarzi - Associate Professor, Mechanical Engineering Department, Bu-Ali Sina University,Hamedan, Iran

Unsteady drag coefficient for oscillated Sphere numerically calculated. Results shown at low frequencies will reach a stable state and for other values of oscillation at low frequencies after a long time, will reach to oscillated drag. The number St = 1 (Strouhal number) at different frequencies (different Reynolds numbers) were investigated that drag coefficient to a maximum of 1.3. The number St = 2 at different frequency, coefficient Drag to a maximum of 2.7.with increasing Strouhal number at the same Reynolds number drag force increases. Compare drag force corresponding to the more frequency for same number of primarily values Strouhal number is more. that`s why greater frequency compression pressure on the body sphere was created and it will be applied on a larger induced drag.

Drag coefficient, Oscillated sphere, Strouhal number