[helly]

Hello
I am doing my first simulation in openfoam using LES approach. based on a tutorial found in internet I am doing the simulation for channel395 and for checking the adequecy of transient solution I am trying to plot CFL and velocity fluctuations. in that tutorial file it is mentioned that I should use gnuplot and type
plot "volavUy2_0"
to have the plot of Uy fluctuation but this file is not generated when I use foamLog. I also checked .foamlog.db and this function is mentioned there and also I activated this line in system/controdict:
fields

U
{
mean on;
prime2Mean on;
base time;
}
but still volavU files are not generated in logs folder. Dose anyone know how I can solve this problem?
Thank you