Numerical approximation of the total drag of a body in a tube

A study is made of numerical methods to approximate the total drag coefficient of an axisymmetric body in a tube. An analytical relationship for the drag coefficient is obtained via a standard open system control volume analysis. This relationship is found to be difficult to apply numerically using available numerical tools, leading to an approximation of the drag coefficient by neglecting the tube wall skin friction and the pressure distribution across the tube radius near the body tail. The resulting drag coefficient approximation, which accounts for tunnel blockage and horizontal buoyancy effects, is found to provide a good estimate to available experimental data for an unheated body. The approximation makes use of currently available numerical codes for axisymmetric inviscid and boundary layer flow. Numerical obtained drag distributions over a range of Reynolds numbers are compared with experimental drag data for the unheated laminar flow body in the Garfield Thomas 48-inch diameter water tunnel.