CFD Studies on Cylindrical Bodies Moving Concentrically Inside Very Long Tubes

The near field flow and drag estimation on cylindrical bodies moving concentrically inside tubes in an incompressible medium always fascinated Naval Platform designers while designing large projectile launchers. This paper presents the flow field numerical simulation on the published experimental work by Naval Underwater System Center, Newport, using the commercially available CFD software FLUENT based on the Reynolds averaged Navier Stokes Equations and k-epsilon turbulence model. Axisymmetric model was used in the simulation without considering appendages such as fins, rudders and propeller. Numerical analysis of such complex confined flows involving relative motion of the bodies is a challenging task. Dynamic mesh was used to solve the relative movement problem of the projectile and tube using user define programme to update the mesh. The results presented include, the characteristics of flow field in the annulus gap, pressure distribution on the moving object and the relation between increased drag and the annulus gap. The simulation results can be employed as reference in designing of such projectiles.