Horizontal Annular Section. Description of the 3D model employed to study the behaviour of barite particles in an annulus based on the CFD approach is as follows.
3D Model: Horizontal Annular Section. The physical model is an annular test section as depicted in Figure 3.
3D Model: Horizontal Annular Section. The minimum flow time from inlet to outlet at a velocity of 0.1524 m/s (lowest annular velocity) is 12 s and 2.4 s for a velocity of 0.762 m/s (highest annular velocity).
Observations from the sectional views on the right indicate that drill pipe rotation results into a uniform distribution of the barite particles in the concentric annular section. Overall, this has a slight effect on the barite accumulation.
As can be observed, the particles further away from the inlet are at a higher velocity than the overall particles in the annular section, still indicating no possibility of barite accumulation.
Nevertheless, the 3D model developed above, to the authors' knowledge, is the first attempt to perform an independent numerical simulation to investigate dynamic barite sag in an annular section. Furthermore, the model based on the CFD-DEM approach is the first attempt to propose the use of the CFD-DEM method for the investigation of barite sag behaviour, keeping in mind that the system is a liquid-solid flow.
Firstly, they assumed that both the radial clearance and the eccentricity of the annular section are small, limiting the application of the expression (Eq.
A composite plot of axial velocity and pressure gradient on a streamline originating from the inlet and terminating at the exit plane of the annular section is used to ensure that steady state flow was achieved across the flow domain.
The additional annular reflector shades part of the aperture, so that the aperture radiates from two annular sections
: between the small and annular reflectors, and between the annular and large reflectors.