An Immersed Boundary Method for flows with evaporating droplets

• Published in: International journal of heat and mass transfer 2019-11, Vol.143, p.118563, Article 118563
• Main Authors: Lupo, Giandomenico, Niazi Ardekani, Mehdi, Brandt, Luca, Duwig, Christophe
• Format: Article
• Language: English
• Subjects: Computational fluid dynamics; Computer Science; Computer simulation; Datalogi; Direct numerical simulation; Droplets; Evaporation; Evaporation rate; Fuel; Gas flow; Immersed boundary; Isotropic turbulence; Laminar flow; Liquid phases; Momentum; Multiphase; Phase change; Spray; Turbulent flow; Vapor phases
• ISSN: 0017-9310; 1879-2189; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2019.118563

•Efficient method for droplet evaporation, using immersed boundary method.•Description of the physical assumptions, model equations, and numerical algorithm of the method.•Validation of evaporating droplet cases in laminar conditions.•Validation of evaporation rate against experiments of a fuel droplet in homogeneous isotropic turbulence. We present a new Immersed Boundary Method (IBM) for the interface resolved simulation of spherical droplet evaporation in gas flow. The method is based on the direct numerical simulation of the coupled momentum, energy and species transport in the gas phase, while the exchange of these quantities with the liquid phase is handled through global mass, energy and momentum balances for each droplet. This approach, applicable in the limit of small spherical droplets, allows for accurate and efficient phase coupling without direct solution of the liquid phase fields, thus saving computational cost. We provide validation results, showing that all the relevant physical phenomena and their interactions are correctly captured, both for laminar and turbulent gas flow. Test cases include fixed rate and free evaporation of a static droplet, displacement of a droplet by Stefan flow, and evaporation of a hydrocarbon droplet in homogeneous isotropic turbulence. The latter case is validated against experimental data, showing the feasibility of the method towards the treatment of conditions representative of real life spray fuel applications.