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At the regions of stasis and flow reversals, there is an important role of motion and deformation in the shear stress calculation [110, 111], concept of the rigid wall condition was assumed due to the negligible effect of shear stress on total DF [112]. The distribution of stresses within the blood was estimated. The stresses ^tσ_ij at time “t” is equal

(1.4)

where

(1.5)

is the viscous stress, ^tμ is viscosity corresponding to the velocity vector ^tv at a spatial point within the blood domain. The viscous stresses are represented by (1.5).

The wall shear stress is calculated as:

(1.6)

where ^tv_t denotes the tangential velocity, and n is the normal direction at the vessel wall. At the integration points near the wall surface, the tangential velocity was estimated first, and then the velocity gradient ∂^tv_t/∂n was calculated. Finally, the viscosity coefficient ^tμ using the average velocity was evaluated. Blood was taken as an incompressible Newtonian fluid, appropriate for larger arteries [110]. The kinematic viscosity was ν = 3.5e−6 m²/s and the blood density was ρ = 1050 kg/m³.