Can FLUENT provide information about the time that the droplets take to reach a surface? Thanks

No one knows? I wonder if I can use UDF to calculate this.

You need to provide a little more information. If it is just a single particle, or a few particles, or course you can track them in Particle Tracking mode to determine when they strike a surface.

This would be tedious for more than 25 or so particles in which case there may be a built-in Fluent summary page.

If you don't find something built-in, you could write a UDF to do it. If you are familiar with UDF's it shouldn't take you more than a day. If not, it could take a week or so.

Thank you so much. It is a jet flow. I think the number of particles is far more than 25. I use surface injection in my model. The summary file does not include the time when they reach the surface I interested. I don't farmiliar with UDF, but I am glad that you said UDF can solve this problem. I will try it. Thanks sooo much!!!