Abstract
The fluid force on a sphere with dimples has been investigated in Reynolds number range from 0.4×10^5 to 1.7×10^5. Two spheres of diameter 42.6 and 100mm were studied with 328 dimples on their surfaces. In the present study, the dimples in the form of circular are were used. The depth ratio of dimple (k/d)(k:the depth of dimple, d:the diameter of sphere) was changed from 0.0079 to 0.0188. The drag on a sphere with dimples was measured using a three components load cell with a strain gage. The pressure distribution around a sphere with dimples was measured using a semiconductor pressure transducer. The velocity distribution near the sphere surface was measured using a hot wire probe. From these results, the relation between the drag and the flow pattern around a sphere with dimples became clear.
