[Wrf-users] Open boundary condition in em_les always results in divergence
Li Xianxiang
lixx at smart.mit.edu
Thu Sep 17 06:08:48 MDT 2009
Hi all,
I am now simulating a hybrid convective/shear PBL using the test/em_les
case as a starting point. The west-east direction was changed to open
boundary condition while the south-north direction continue using
periodic condition. The input sounding was changed to the
input.sounding.meanwind provided with WRFV3.1.1 with a geostrophic wind
at 10 m/s. The heat flux from ground is 0.24 Km/s. The time step was
reduced to 1/2 s (or even 1/4 s). The problem is that the calculation
always get diverged at about 11 minutes at the east boundary. The
vertical velocity there becomes very large and CFL number exceeds 2.
Finally the wind field has many 'NaNf' in the output file. The error
message is something like:
d01 0001-01-01_00:11:49 1 points exceeded cfl=2 in domain d01
at time 0001-01-01_00:11:49 hours
d01 0001-01-01_00:11:49 MAX AT i,j,k: 99
65 24 vert_cfl,w,d(eta)= 2.498336 64.77351 1.0101020E-02
d01 0001-01-01_00:11:49+01/02 5 points exceeded cfl=2 in
domain d01 at time 0001-01-01_00:11:49+01/02 hours
d01 0001-01-01_00:11:49+01/02 MAX AT i,j,k:
99 65 24 vert_cfl,w,d(eta)= 9.178696
-204.4505 1.0101020E-02
d01 0001-01-01_00:11:50 142 points exceeded cfl=2 in domain
d01 at time 0001-01-01_00:11:50 hours
d01 0001-01-01_00:11:50 MAX AT i,j,k: 99
65 24 vert_cfl,w,d(eta)= 41.67853 634.0490
1.0101020E-02
I attach my namelist.input file below for your reference. I will
appreciate it if anyone could provide me some solutions or suggestions.
Best regards,
Xianxiang LI
The namelist.input file reads:
&time_control
run_days = 0,
run_hours = 6,
run_minutes = 00,
run_seconds = 00,
start_year = 0001, 0001, 0001,
start_month = 01, 01, 01,
start_day = 01, 01, 01,
start_hour = 00, 01, 00,
start_minute = 00, 30, 00,
start_second = 00, 00, 00,
end_year = 0001, 0001, 0001,
end_month = 01, 01, 01,
end_day = 01, 01, 01,
end_hour = 01, 02, 00,
end_minute = 00, 30, 00,
end_second = 00, 00, 00,
history_interval_m = 10, 10, 1,
history_interval_s = 00, 00, 1,
frames_per_outfile = 1000, 1000, 1000,
restart = .false.,
restart_interval_m = 120,
io_form_history = 2
io_form_restart = 2
io_form_input = 2
io_form_boundary = 2
debug_level = 0
/
&domains
time_step = 0,
time_step_fract_num = 1,
time_step_fract_den = 2,
max_dom = 1,
s_we = 1, 1, 1,
e_we = 100, 100, 151,
s_sn = 1, 1, 1,
e_sn = 100, 100, 151,
s_vert = 1, 1, 1,
e_vert = 100, 100, 41,
dx = 50, 50, 16.6667,
dy = 50, 50, 16.6667,
ztop = 2000, 2000, 2000,
grid_id = 1, 2, 3,
parent_id = 0, 1, 2,
i_parent_start = 0, 10, 15,
j_parent_start = 0, 10, 15,
parent_grid_ratio = 1, 3, 3,
parent_time_step_ratio = 1, 3, 3,
feedback = 0,
smooth_option = 0
/
&physics
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,
ifsnow = 0,
icloud = 0,
num_soil_layers = 5,
mp_zero_out = 0,
/
&fdda
/
&dynamics
rk_ord = 3,
diff_opt = 2,
km_opt = 2,
damp_opt = 0,
zdamp = 5000., 5000., 5000.,
dampcoef = 0.1, 0.2, 0.2
khdif = 1., 1., .05,
kvdif = 1., 1., .05,
c_s = 0.18
c_k = 0.10
mix_isotropic = 1
smdiv = 0.1, 0.1, 0.1,
emdiv = 0.01, 0.01, 0.01,
epssm = 0.1, 0.1, 0.1
tke_heat_flux = 0.24, 0.24, 0.24,
time_step_sound = 6, 6, 6,
h_mom_adv_order = 5, 5, 5,
v_mom_adv_order = 3, 3, 3,
h_sca_adv_order = 5, 5, 5,
v_sca_adv_order = 3, 3, 3,
mix_full_fields = .true., .true., .true.,
non_hydrostatic = .true., .true., .true.,
pert_coriolis = .true., .true., .true.,
/
&bdy_control
periodic_x = .false., .false.,.false.,
symmetric_xs = .false.,.false.,.false.,
symmetric_xe = .false.,.false.,.false.,
open_xs = .true.,.false.,.false.,
open_xe = .true.,.false.,.false.,
periodic_y = .true., .false.,.false.,
symmetric_ys = .false.,.false.,.false.,
symmetric_ye = .false.,.false.,.false.,
open_ys = .false.,.false.,.false.,
open_ye = .false.,.false.,.false.,
nested = .false., .true., .true.,
/
&grib2
/
&namelist_quilt
nio_tasks_per_group = 0,
nio_groups = 1,
/
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