Inclination Angle Effect and Separation Zones Estimation for Incompressible Flows inside Pipes using Sub-Grids Refinement

摘要

The particular characteristics of flows inside channels present high interest to the industrial sector concerning pipes design, construction, corrosion and control issues. In the present paper the numerical estimation and investigation of incompressible viscous flows inside inclined step pipes are approached trying to produce accurate flow variables results and certain data concerning the separation zones and the inclination angle effect according to the various Reynolds numbers values. Cartesian grids are generated for the domain discretization in combination with a block-nested refinement technique, trying to avoid the huge computational memory is needed when the aspect ratio of the physical domain is high enough. The angle effect is investigated concerning the recirculation zones and the energy flow losses, trying to predict the optimum geometrical selection of pipes related to the flow rate, hydraulic diameter and inclination angle. The Navier - Stokes equations are solved using an artificial compressibility method in combination with upwind numerical schemes. Various results are presented for several grid sizes and Reynolds numbers for four different inclination step angles. It seems that this flow is characterized by extended recirculation zones even at low Reynolds numbers, but using the appropriate step angle according to the flow rates values the energy losses can be minimized.