Simulations of Solid-Liquid Scalar Transfer for a Spherical Particle in Laminar and Turbulent Flow

Scalar transfer from a solid sphere to a surrounding liquid has been studied numerically. The simulation procedure involves full hydrodynamic resolution of the solid–liquid interaction and the flow (laminar and turbulent) of the carrier
fluid by means of the lattice-Boltzmann method. Scalar transport is solved with a finite volume method on coupled overlapping domains (COD): an outer domain discretized with a cubic grid and a shell around the solid sphere with a spherical grid with fine spacing in the radial direction. The shell is needed given the thin scalar boundary layer around the sphere that is the result of high Schmidt numbers (up to Sc 5 1000). After assessing the COD approach for laminar benchmark cases, it is applied to a sphere moving through omogeneous isotropic turbulence with the sphere radius larger (by typically a factor of 10) than the Kolmogorov length scale so that it experiences an inhomogeneous hydrodynamic environment. This translates in pronounced scalar concentration variations and transfer rates over the sphere’s surface. Overall scalar-transfer coefficients are compared to those derived from classical Sherwood number correlations.