CFD simulation of wall-bounded laminar flow through screens. Part I: Hydrodynamic characterization

Abstract

This paper characterizes the hydrodynamics of laminar flows through circular ducts equipped with plain square woven meshes/screens in their role as static mixers. The CFD model was used to investigate the effect of screen geometry, number of screens, inter-screen spacing, and operating conditions on the velocity and pressure fields. This work therefore presents an analysis of the velocity contours, streamlines, and profiles at various locations within the pipe in addition to the pressure profiles to obtain a better understanding of the complex behavior of the flow. The presence of screens normal to the flow was found to alter the fully developed parabolic profile and flatten it both upstream and downstream, hence simultaneously decelerating and accelerating regions in the cross-sectional area of the flow. Downstream of screens, the velocity profile was characterized by a sinusoidal shape that quickly decays, and vortices were observed under certain operating and design conditions. The study of the pressure field helped delineate the contribution of static and dynamic pressures in addition to identifying a minimum inter-screen distance if maximum pressure recovery is desired. Predictions of the pressure drop for various mesh geometries and under different operating conditions were validated using empirical correlations and the results reflected a very good accuracy with the maximum relative error falling within ± 7.3%. © 2020 Elsevier Masson SAS