Multiphase Environmental Flows - Essay Example

The other method involves the use of the Eulerian/ Lagrangian method in which the particles are treated individually or as a group tracked by the Lagrangian frame of reference. Cundall and Starck developed the discrete element method in 1979 and have been widely used for the study of particles in the solid state. Studies conducted using DEM coupled with CFD showed that particles move in plugs along the conveying pipes.

According to Kuang et al (2008), one of the most important technologies in the industry is dense phase pneumatic transportation of bulk material in the slug form. In his research paper, Kuang et al (2008) focus on the numerical study of the slug flow in horizontal pneumatic convey using discrete particle simulation. Low velocity and dense gas systems common in industries such as mineral processing, agricultural industries and, chemical industries. Slug flow is used in the industry to transport materials from one location to another. The slug flow is particularly considered in industries because of its ability to reduce the degradation of plants also reduce wear. The power utilization of the system is also superior as compared to other flows. The study and simulation of the slug flow, therefore, brings into light the nature of flow to understand the system and improve it.

According to the research done by Kuang (2008), the particles used were spherical, made of polythene material with a diameter (DP) of  the particle density (pp) was 922 Kgm-3.air was used for the gas phase. The viscosity was taken to be  and a density of . The underlying equations for particle flow were the rotational and translation motion determined by Newton’s laws of motion given as.

Where mi is the mass, Ii is the momentum or rotation inertia, is the rotational velocity while  is the translational velocity of the particles (Kuang et al, 2008). For the gas phase, the gas flow was considered as a continuous phase and the governing equations are as shown below.The coupling method used in KuanKuang's08) simulations was both DEM and CFD. At an individual particle scale, modeling of the flow was done using DEM while the gas flow modeling was done using CFD.