Interface-resolved detailed numerical simulation of evaporating two-phase flows with robin boundary conditions on irregular domains. (December 2019)

• Record Type: Journal Article
• Authors: Chai, Min; Luo, Kun; Shao, Changxiao; Wang, Haiou; Fan, Jianren
• Is Part Of: International journal of heat and mass transfer. Volume 145(2019)
• Publication Date: 2019-12
• Subjects: Non-uniform evaporation -- Level set method -- Interface-resolved evaporation model -- Ghost fluid method -- Robin boundary condition; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2019.118774
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: An interface-resolved DNS framework for evaporation with Robin conditions is built. The revised heat flux based evaporation model is applied to improve the predictions. The interface-resolved DNS framework proves to be accurate and grid convergent. Non-uniform evaporation is studied to reveal the advantages of the framework. 3D validations are performed and comparisons between 2D and 3D results are made. Abstract: In this paper, our previous finite difference discretization method for Robin boundary conditions is implemented into an interface-resolved detailed numerical simulation framework to solve evaporation problems on an irregular interface. The framework utilizes a conservative level set method for describing the interface, a ghost fluid method for addressing the discontinuities on the interface, and a revised heat flux based model for predicting the evaporation rate to improve the accuracy, stability and applicability of the simulations. Specific care has been devoted to the accurate treatments of the involved complex boundary conditions on the interface. Numerical results are in excellent agreements with the analytical solutions, indicating the success of the methods for the above-mentioned sub-processes coupled with the fluid solver. The numerical framework is robust and achieves first-order overall convergence accuracy. Then, the non-uniform evaporation of single droplets is simulated to demonstrate the fascination of such an interface-resolved framework on in-depth understanding of physical mechanisms and therefore on modification of traditional evaporation models. Finally, rigorous validations are conducted in a three-dimensional configuration of droplet evaporation. In summary, the framework proposed in this paper represents a promising tool for non-uniform evaporation modelling, which will be applied to more practical problems in future work.