Velocity field and thickness of a laminar boundary layer at the core‐mantle boundary

Abstract

Steady velocity estimates for the core fluid make possible new input data to the boundary layer equations that describe a flow field at the core‐mantle boundary (CMB). Low valued estimates of the core fluid viscosity are adopted to solve the equations with large dimensions of 3000–6000 km or, alternatively, smaller scale lengths of 10 m of CMB topography which are used to make boundary layer thickness estimates of 163.6 and 0.2988 m for the large and small models, respectively. The laminar velocity flow field within the layer thickness is calculated according to a numerical method developed for parabolic equations and is slower and thicker than boundary layers modelled in the same way for alternate atmospheric and benthic conditions. The model uses a zero pressure gradient and a flat rigid wall for the calculations to simplify this analysis. The surface topography at the CMB may alter the velocity field and produce turbulence.