Modeling approach of flowing condensate coverage rate on inclined wall for aerosol wash down

•A flowing condensate coverage rate modeling approach is proposed.•An expression of equivalent Marrangoni force on a moving droplet is proposed.•A transition criterion of droplet transforming to rivulet is proposed.•The coverage rate modeling is validated, which indicates a good agreement.•The new model is applied to a basic and prototypical nuclear containment accident. The flowing condensate coverage on inclined wall is a significant factor for evaluating the aerosol wash down process in the containment. In this paper a modeling approach of condensate coverage rate is proposed. This approach contains a microscopic treatment (including droplet model, transition criterion and rivulet model) and a macroscopic treatment. The derived parameters, e.g. coverage rate, are in terms of volume flow rate, contact angles, inclination and fluid properties, and can be easily implemented into the containment analysis programs. This approach is validated by several existing experimental data. The comparison results show generally good agreement of the modeling approach with experimental data. Furthermore, the numerical results of a basic case are presented and discussed.