DEVELOPMENT OF A BOUNDARY CONDITION WALL FUNCTION FOR PARTICULATE FOULING CFD MODELING

Modelling of mass transfer of particles to solid surfaces is a considerable challenge in most industrial processes. Using computational fluid dynamics (CFD) directly on these applications is very challenging and costly due to the grid refinement required to capture the complex physical processes that dominate in the near-wall region. We propose a detailed boundary layer model, which can couple the detailed physics in the wall region with the external flow. This mass-transfer wall function can be applied as a boundary condition for coarse grid CFD models. The detailed boundary layer model incorporates external forces, turbulence and hydrodynamic lift and drag. In addition we include the effects of Brownian diffusion, thermophoresis, XDLVO forces and the inter-particle collisions. The particle deposition flux to the wall is modified with an effective adhesion probability, caused by the adhesive forces and the turbulent shear stress statistics. NOMENCLATURE A Total drift velocity, m s. B Total diffusion coefficient, 2m s. LC Lift coefficient, dimensionless. pC Specific heat capacity, J kg K. d Diameter, m. l l l lf P d Shear stress probability density function, dimensionless. f Force vector per unit volume, 3N m. F Force vector, N. g Gravity, 2m s. h Particle-wall separation, m.,p lh Particle-liquid heat transfer coefficient, 2W m K. J Mass flux, 2kg m s. Bk The Boltzmann constant, 231.3807 10 J K . hk Thermal conductivity, W m K