[smnitro]

Hi All,

I have a case with a bluff body inside of a wind tunnel. I am running this as an unsteady simulation. I am using the Detached Eddy Simulation model with K-W-SST. The boundary conditions are walls for the body and the walls of the wind tunnel. Inlet is a pressure inlet and outlet is a pressure outlet. The outlet pressure and the operating conditions are both 0 pa.

I am trying to recreate simulations run on a different solver, so I know the correct Cd and Cm

I am setting up the lift monitor with these commands, the first 1 being a wall-id.

set-drag-monitor

yes
1

yes
yes
"cdOut"
yes


1
0
0
monitor-unsteady
yes

The result I am getting is that the Cl and Cd values are converging within about 400 iterations, instead of fluctuating with the vortices that should be forming. I have run till 30,000 iterations and there is no fluctuations that are occuring. (there are 35 sub iterations for every time step)

Also, as the time step is decreasing in size the Cd values are increasing by an order of magitude (0.1 s -> 1 Cd, 0.001 ->10 Cd , 0.0001 -> 100 Cd)

Any pointers at what could be wrong or what else I could look at? Thanks y'all!

This is my input commands:

/file/read-case CASE_NAME
mesh
check
q
q
define
boundary-conditions
modify-zones
zone-type
wall-3
pressure-outlet
zone-type
wall-2
pressure-inlet
q
pressure-inlet



149.958









q
operating-conditions
operating-pressure
0
q
q
define
models
viscous
detached-eddy-simulation
yes
sst-k-omega
q
unsteady-2nd-order-bounded
yes
q
q
solve
monitors
residual
convergence
0.0000001
0.0000001
0.0000001
0.0000001
0.0000001
0.0000001
n-save
10000000
plot
yes
print
yes
q
q
init
set-defaults
k
0.00104
omega
7830
x-velocity
15.6464
q
init
q
set
max-iterations-per-time
35
reporting
1
number-of-time-steps
10000
time-step
0.107
data-sampling
yes
1
yes
yes
q
initialize
init
ok
q
set
/file/write-case-data
CASE_OUTPUT_FILENAME
q
q
report
reference-values
area
0.034403157
length
0.23368
pressure
149.958
velocity
15.6464
viscosity
0.0000181205
temperature
288.15
density
1.2251
q
system
proc-stats
sys-stats
q
q
file
auto-save
append-file-name-with
time-step
6
data-frequency
10
case-frequency
if-case
q
q
1
solve
monitors
force
set-drag

yes
1

yes
yes
"cdOut"
yes


1
0
0
set-moment

yes
1

yes
yes
"cmOut"
yes


0
0
0
0
0
1
set-lift-monitor

yes
1

yes
yes
"clOut"
yes


0
0
1
monitor-unsteady
yes
list-monitors
/solve
iterate
1000
/file/write-case-data
OUTPUT_FILENAME
/exit yes