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WRF-LES CFL violation


New member

I've been trying to run some WRF-LES simulations at 50-25m resolution but seem to be having some trouble getting around some cfl violations. I am able to run a 200x300 point domain with 100m resolution no problem, but anything lower than that causes a stream of CFL violations. I have tried setting my e_vert from 40 to 200 using a 2000m ztop. They all seem to have similar CFL violations though.

I copied the /test/em_les/namelist.input physics section:
mp_physics = 0, 0, 0,
ra_lw_physics = 0, 0, 0,
ra_sw_physics = 0, 0, 0,
radt = 0, 0, 0,
sf_sfclay_physics = 1, 1, 1,
sf_surface_physics = 0, 0, 0,
bl_pbl_physics = 0, 0, 0,
bldt = 0, 0, 0,
cu_physics = 0, 0, 0,
cudt = 0, 0, 0,
isfflx = 2,

I've also tried varying the amount of cpu cores dedicated to the job. Sometimes, it can error out if there are too many cores.

Any other suggestions for running high resolution WRF-LES simulations?

Attached are my name list. My rsl.error log is too large to attach but I can post some of it if anyone needs.



  • namelist.input
    6.3 KB · Views: 13
I suppose this is an ideal LES case. Please le the know if I am wrong.
I would suggest you reduce the time step. For dx =60, the maximum time step should be 0.36 (s)
Please change the settings as
time_step = 0,

time_step_fract_num = 36,

time_step_fract_den = 100,

Then try again.
Could someone help me, I'm trying to start experimenting with WRF-LES but I'm new in this micro area, any manual for beginners? Or a page that gives a north on how to check the LES round after the WRF round? Very grateful in advance!

anyone can help me ?