Experimental and Numerical Study on Air Flow Behavior for a Novel Retractable Reverse Circulation Drill Bit of Casing-while-Drilling (CwD)

Table 1

Mesh independence results.

Number of mesh elements (million)	Mass flow rate at inlet, (kg/h)	Mass flow rate sucked into the drill bit, (kg/h)
0.3	184.3	56.9
0.5	184.3	50.8
0.7	184.3	47.9
0.9	184.3	46.8
1.1	184.3	44.6
1.3	184.3	44.6