Experimental and numerical investigation of drag force over tubular frustum

There are different ways in order to achieve higher velocity in underwater vehicles. one of these methods is using a body with special form. this paper presents a towing tank based experimental study on drag forces for different reynolds numbers of a special undeiwater model. this paper investigates drag force and drag coefficient in a different flow direction over the model. obtained experimental results in towing tank are explained. computational fluid dynamic (cfd) simulation also is performed using commercial cfd software package fluent 6.3.26. there is a significant decrease in drag coefficient of model moving with small diameter at upstream.