Numerical Analysis of Turbulent Structure Developing in Circular Pipe Containing One Rod Located Off-Center.

Abstract

A numerical analysis has been performed on turbulent flow developing in a circular pipe containing one rod located off-center. In calculation, an algebraic stress model was adopted in order to predict Reynolds stresses precisely, and the boundary-fitted coordinate system was introduced to set the boundary condition. The Reynolds number in this calculation is the same as that in the experiment. Calculated results were compared with the experimental data available. The calculated profiles of secondary flow and Reynolds stresses for developing turbulent flow are shown in detail. As a result of this calculation, it was found that the calculated distributions of the streamwise velocity and friction velocity are predicted well. Moreover, the calculated result suggests that a pair of vortices are generated by anisotropic turbulence in the region between the off-center rod and circular pipe. As a characteristic feature, it is pointed out that the intensity of secondary flow is maximum before becoming a fully developed turbulent flow. The location at which it is maximum corresponds to that of the appearance of a merged boundary layer. In addition to these results, the production terms of secondary flow in the vorticity equation are evaluated using calculated results in order to provide further understanding of the generation of secondary flow.