Modeling Impingement

Impingement of a Lagrangian Phase

For simulations where the Lagrangian Multiphase model is selected and fluid droplets are present, fluid films can be formed. These films form when the fluid droplets impinge the interface between a fluid film shell region and the fluid region.

For consistency, use the same materials for the fluid film and Lagrangian phases. Although differences in material properties are allowed between the phases, avoid these differences. They would lead to improper conservation of mass or enthalpy. If the densities of the phases differ, volume is not conserved.

Impingement of a Dispersed Phase

The Dispersed Multiphase model can be used as a lightweight replacement for Lagrangian particles in simulations where the Lagrangian Multiphase model is too computationally expensive due to the large number of particles. Impingement transfers droplets from the dispersed phase of a Dispersed Multiphase simulation into the fluid film phase. Using Dispersed Multiphase particles for icing and soiling simulations is significantly quicker than using Lagrangian particles. However, only single-component liquid phases are supported.

Impingement of a Eulerian Phase

For simulations where the Eulerian Multiphase (EMP) model is selected and a liquid Eulerian phase is present, the Film-Eulerian Phase Interaction model supports droplet impingement from the Eulerian phase into a fluid film domain. Both single-component and multi-component liquid phases are supported.

Two impingement models are available:

• Incident Mass Flux Impingement model

  This is a simplistic model and does not represent accurate physics. You specify the impingement efficiency, that is, the fraction of the total mass impinging on the fluid film boundary that is transferred from the Eulerian phase into the fluid film.

• Caraghiaur Impingement model

  This is a mechanistic model for impingement, and uses the local concentration of droplets and the droplet fluctuating velocity.

For more information on the Incident Mass Flux Impingement model and the Caraghiaur Impingement model, see Impingement.

Impingement of a Mixture Multiphase (MMP) Phase

For simulations where the Mixture Multiphase (MMP) model is selected and a liquid Eulerian phase is present, the Film-MMP Phase Interaction model supports droplet impingement from the Eulerian phase into a fluid film domain. Both single-component and multi-component liquid phases are supported.

Only the Incident Mass Flux Impingement model is available. You specify the impingement efficiency.

For more information on the Incident Mass Flux Impingement model in Mixture Multiphase (MMP) simulations, see Incident Mass Flux Impingement.