Numerical simulation of drilling fluid flow in annular the space of the borehole.
Vol. 32, no. 4 (2015), s. 775-782, 
This paper presents the numerical results of a numerical analys is of drilling fluid flow through annular space in the borehole. The analysis used the Herschel–Bulkley rheological fluid model. The obtained results of the analysis for three cases with variable geometry. Variable geometry is associated with a larger diameter drill in the joints of drill pipes, and consequently, with reduced flow cross-section. A comparison of pressure values at the end of the analyzed examples showed that in the example of a simple drill pipe with out joints, pressure values were 30% higher than in the case, which takes into account changes in the geometry of the joints.