What do eta_mean, u_mean, and v_mean represent in the RIP_2D_FOAM example?

[hadley lau]

Dear FUNWAVE Users,

I ran the funwave_tvd with the rip_2d_foam test case and found that its output includes files such as eta_00000~eta_00033, etamean_00000~etamean_00018, u_00000~u_00033, umean_00000~umean_00018, v_00000~v_00033, vmean_00000~vmean_00018. From the literal meaning, I assume "mean" refers to the average. I would like to know what the averages of eta, u, and v represent. I tried checking the official FUNWAVE-TVD documentation (FUNWAVE-TVD USACE Version) but could not find any relevant description. Is there a document that explains this, or could you help me with an answer here? Thank you very much!