Numerical simulation of secondary flow in pneumatic conveying of solid particles in a horizontal circular pipe

Abstract

-Under certain conditions, a fully developed turbulent flow in a straight pipe may show a secondary flow; for instance, when non-circular cross-section or non-uniform wall roughness around the perimeter of the duct are considered. In horizontal pipe particle-laden gas flow, the non-uniform forcing of the flow by the solids entrained in the gas core may also drive a secondary flow, even with uniform wall roughness along the circumferential direction. In this paper, the effects of wall roughness, particle size and particle mass loading ratio on the secondary flow developing in a horizontal pipe of circular cross-section under turbulent conditions are analysed. The computations are based on the Euler-Lagrange approach accounting for wall roughness and inter-particle collisions (i.e., four-way coupling). In the case of inertial particles, if interparticle collisions are disregarded, the secondary flow consists of two recirculation cells with an upward flow near the vertical (symmetry) axis and a downward flow close to the walls. On the other hand, when interparticle collisions are accounted for, the pattern depends on the particle concentration profile: with relatively smooth walls (low roughness), two recirculation cells are found, but with rough walls four recirculation cells are generated. For smaller particles, a transition between two and four recirculation cells in the secondary flow is observed by increasing the mass loading ratio.

Numerical simulation of non-Newtonian blood flow dynamics in human thoracic aorta

“…Laín and Aliod 2000;Laín et al 2009;Laín and Osorio 2010;Laín and Sommerfeld 2013) have enabled the use of three-dimensional (3D) numerical simulations to investigate patient-specific haemodynamics and to understand the origin and development of different CVDs. However, in spite of the last decade history of CFD studies related to the TA, human blood has been usually treated as a Newtonian fluid.…”

Parameters influencing dilute‐phase pneumatic conveying through pipe systems: A computational study by the Euler/Lagrange approach

“…Thereby, the influence of different effects, such as degree of wall roughness, pipe diameter, particle mass loading, particle size distribution and conveying velocity, on pneumatic conveying through the pipe system were thoroughly studied. [21][22][23][24][25][26] After validation against experiments, the present contribution summarizes briefly numerical results on the influence of wall roughness and inter-particle collisions on spherical powder conveying through a horizontal pipe, a pipe bend and a vertical pipe. Here also the influence of horizontal pipe length and hence bend inlet conditions are presented, considering the particle phase distribution in the pipe cross-section within and downstream of the bend.…”

Solid Particles Injection in Gas Turbulent Channel Flow

“…In a simulation process of horizontal flow in a pipe with the inner diameter of 30.5 mm [13], the results were observed at a section corresponding to a fully developed pattern. The dispersed phase was plastic pellets with the density of 1020 kg/m 3 and two different diameters of 200 µm and 50 µm.…”

“…In the two-way coupling, both of the two phases exchange the effects with each other [12]. In the four-way coupling, the effect of particles collisions is incorporated [13] [14]. The particles motion might be classified according to the mechanisms which govern the particles motion.…”