New results on turbulent wall layers and dispersion for Herschel-Bulkley fluids in weakly turbulent flows

Very good agreement of analytical velocity profile in the wall layer with the DNS data available.

Increasing yield stress and low power law index retards transition and thins the viscous wall layer.

The precise shape of turbulent diffusivity has only minor effect in Taylor dispersion.

Larger power law index and moderate yield stresses can have wall layer thickness over 10% of the radius.

This leads to an order of magnitude increase in Taylor dispersion coefficients over highly turbulent values.

Significant consequences for cementing of oil and gas wells.