Loading multiple stl files

Hello all,

I would like to simulate particles in a container that are stirred by to stirrers. The container is available in an stl file and so are the two stirrers. So, in total, I've got three stl files. I assume that splitting the whole geometry into 3 parts is necessary, since the two stirrers are supposed to have different angular velocities and the container is at rest.

While importing the second stl and and applying the fix wall/gran/hooke I get the following error message:

ERROR: There must be only one fix wall/gran with style 'mesh/gran'

The error message is issued by FixWallGranHooke::FixWallGranHooke().

Now my questions: Is there anything wrong with how I've set up the input file? Is there a workaround such that I can import 3 stl files and make two of those geometries rotate? If I have to modify the code: how should I approach the whole thing?

Thanks for your answers! Best,
Moritz

PS: Here is my input file.

log log.alpha2.n14587
atom_style granular
boundary f p f
newton off
communicate single vel yes
units si
region wholeSystemRegion block -0.2751 0.6561 -0.09351 0.09351 -0.2749371 0.510
create_box 1 wholeSystemRegion
neighbor 0.01 bin
neigh_modify delay 0

# Material properties
fix m1 all property/global youngsModulus peratomtype 5.e6
fix m2 all property/global poissonsRatio peratomtype 0.45
fix m3 all property/global coefficientRestitution peratomtypepair 1 0.5
fix m4 all property/global coefficientFriction peratomtypepair 1 0.5
fix m5 all property/global characteristicVelocity scalar 2.

# pair style
pair_style gran/hooke 1 0
pair_coeff * *

# integration settings
timestep 0.00005
fix 1 all nve/sphere

# geometry
fix fixGrav1 all gravity 9.81 vector 0.0 0.0 -1.0

fix wallStl all mesh/gran geo_0.stl 1 0.001 0 0 0 0 0 0
fix wallStlWall all wall/gran/hooke 1 0 mesh/gran 1 wallStl

fix leftStirrerStl all mesh/gran geo_1.stl 1 0.001 0 0 0 0 0 0
fix leftStirrerStlWall all wall/gran/hooke 1 0 mesh/gran 1 leftStirrerStl

fix rightStirrerStl all mesh/gran geo_2.stl 1 0.001 0 0 0 0 0 0
fix rightStirrerStlWall all wall/gran/hooke 1 0 mesh/gran 1 rightStirrerStl left

# thermo settings
compute 1 all erotate/sphere
thermo_style custom step atoms ke c_1
thermo 1000
thermo_modify lost ignore norm no
compute_modify thermo_temp dynamic yes

# pour in particles
region pourRegion block -0.27 0.65 -0.09 0.09 0.2 0.5 units box
group nve_group region wholeSystemRegion
fix insert nve_group pour 14587 1 12345 diam uniform 0.012 0.012 dens uniform 11

# dump
run 1
dump dumpParticles all custom 200 post/dump.fill.alpha2.n14587 id type x y z ix
dump dumpStl all stl 200 post/dump.fill*.stl
run 10000 upto