Adaptive time step and CFL error

[raymassum]

In my WRF simulations, if in the nested domain (i.e. 3rd domain) dt crosses 0.1 sec then CFL error is coming. Whereas, 1st and 2nd domain can run sucessfuly with dt=15 sec. Therefore, is there any way to restrict the timestep differently in different domain?
I am also wondering is an adaptive time step is helpful in this case.

For this I set like this in namelist, please help me to correct it


use_adaptive_time_step = .true.,
step_to_output_time = .true.,
target_cfl = 1.2, 1.2, 1.2,
max_step_increase_pct = 5, 5, 5,
starting_time_step = 1,
starting_time_step_den = 5,
max_time_step = 15, 15, 1,
max_time_step_den = 1, 1, 10,
min_time_step = 0,
min_time_step_den = 10,
adaptation_domain = 3,
feedback = 1,
smooth_option = 2,
smooth_cg_topo = .true.

 

[kwerner]

Using adaptive time step may be helpful in this case. Did you try the settings you have above to see if that works?

 

[raymassum]

Yea. I have tried it. But due to dt= 0.1 limit in 3rd domain, model is taking excessive time to run. Increasing no of processor is not helping. Is there any way to make it fast?
Thankyou for your reply @kwerner

 

[kwerner]

I'm not sure if there is a way to increase the speed. Can you share your full namelist.input file and let me the range of the number of processors you've tried using?