## 1 Introduction  
With the increasing demand for oil and gas resources and the continuous progress in production methods, extended-reach and horizontal well technology have made remarkable developments [1, 2]. However, during extended-reach and horizontal well drilling, it is easy for drill cuttings to be deposited in the horizontal well section, resulting in a cuttings bed. With the increase in drilling time, the accumulation and thickening of the cuttings bed can easily cause drilling problems such as pipe sticking, high torque, and drag [3, 4]. This will increase the drilling risk, limit the horizontal well's extension capacity, and significantly increase the drilling period and cost [5, 6, 7]. The hole cleaning device can effectively remove the cuttings bed during extended-reach and horizontal well drilling. It can accelerate the flow of drilling fluid. At the same time, the rotation of the hole cleaning device can form a vortex in the spiral channel, which is more conducive to removing drill cuttings, improving the circulation velocity in the annulus, and effectively eroding the cuttings bed. The combination of mechanical rotation and hydrodynamic eddy current effect of the hole cleaning device can effectively remove cuttings and ensure the hole cleaning effect. Such research for hole cleaning devices has been rapidly developing worldwide in recent years. In 1999, Halliburton developed and produced the cuttings bed Impeller (CBI). Its main structure includes a tool body, herringbone diversion groove, and transition section. The CBI mainly comprises the body, the transition slope diversion, the neck, the export diversion slope, the spiral-shaped impeller, the spiral-shaped groove, and the inlet diversion slope [8; 9]. Later, VAM Drilling company launched a HydrocleanTM particular structure drill pipe to solve the cuttings bed accumulated in the highly deviated and horizontal sections. The hole cleaning mechanism of HydroleanTM particular structure drill pipe uses the mechanism of mechanical scraping and hydraulic lifting of drilling fluid. When drilling the highly deviated and horizontal wells, the high-speed rotation of the spiral blade will generate a circumferential force outside the blade (the force depends on the rotating drill pipe) to stir the cuttings bed. Using HydrocleanTM can improve the hole cleaning efficiency by 55% to 60%, reduce the torque and drag by 25% to 35%, and reduce the annular pressure consumption by more than 45% [10; 11]. Recently, [PERSON] et al. [12] simplified the hole cleaning device into a straight blade; obtained the decay mechanism of spiral flow; and evaluated the hole cleaning effect under different helix angles, blade heights, and rotational speeds. [PERSON] et al. [13] used the CFD method to obtain the effective action distance of a straight-blade type hole cleaning device under different parameters and took the effective action distance to evaluate the hole cleaning effect. The numerical results showed that the hole cleaning device has a sound hole cleaning performance. With such in-depth study about the design and optimization of hole cleaning devices, people's theoretical understanding of them is deepening [14]. However, detailed research on the existing V-blade hole cleaning devices in the drilling engineering field is limited. At the same time, most of the drilling fluid is non-Newtonian fluid [15; 16]; the decay characteristics of device-induced spiral flow in a non-Newtonian fluid, flow pattern distribution behind the blade, and the hole cleaning effect are not completely clear. In this paper, the solid-liquid flow characteristics of a V-shaped hole cleaning device were simulated utilizing CFD approach. The decay law of spiral flow induced by the V-shaped hole cleaning device was obtained by changing the rotational speed, fluid consistency coefficient, and helix angle. In addition, the annular cuttings concentration distribution under different parameters was also obtained.