Variation of drag coefficient on rough cyclindrical bodies

Abstract

The accurate assessment of drag force on bodies of different configuration enable us better design of structures like buildings, chimney, towers, aeroplanes, automobiles etc. Drag coefficient is a function of speed, flow direction, object position, object shape and size, fluid density and fluid viscosity. Many factors affect the overall drag coefficient for vehicles, such as the following: (1) the shape of the bodies (leading and trailing edges), or nose, of the vehicle. (2) The surface roughness of the bodies. (3) Such appendages as mirrors, door handles, antennas, and so forth. Drag is a function of relative speed, flow direction, placement of the object, object configuration (shape and size), fluid density, fluid viscosity and roughness of the surface of the bodies. There have been persistent efforts to decrease the above problems by the use of drag force and pressure distribution of cylindrical bodies. A review of literature reveals that some investigations relating to aerodynamics quality have been carried out in cylindrical bodies. Although these examinations have thrown some graceful on the performance of definite conclusions (qualitative /quantitative) have not been arrived at as regards their improved performance on a comparative basis with respect to a conventional drag force. The literature provides limited quantitative study on the effect of roughness on related parameters in cylindrical bodies’ viz. different diameter of cylinder, different size of roughness and free streamed velocity.