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Added viscosity estimate from diagonal shear stress 

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@11936 f3b2605a-c512-4ea7-a41b-209d697bcdaa
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athomps 2014-05-07 16:05:35 +00:00
parent 53db68362e
commit 4ab16d5388
1 changed files with 15 additions and 4 deletions
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19
examples/VISCOSITY/in.gk.2d
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@ -49,17 +49,28 @@ unfix 2
reset_timestep 0
# Define distinct components of symmetric traceless stress tensor
variable pxy equal pxy
variable pxx equal pxx-press
fix SS all ave/correlate $s $p $d &
v_pxy type auto file profile.gk.2d ave running
v_pxy v_pxx type auto file profile.gk.2d ave running
# Diagonal components of SS are larger by factor 2-2/d,
# which is 4/3 for d=3, but 1 for d=2.
# See Daivis and Evans, J.Chem.Phys, 100, 541-547 (1994)
variable scale equal 1.0/$t*vol*$s*dt
variable v11 equal trap(f_SS[3])*${scale}
variable diagfac equal 2-2/2
variable vxy equal trap(f_SS[3])*${scale}
variable vxx equal trap(f_SS[4])*${scale}/${diagfac}
thermo_style custom step temp press pxy v_v11
thermo_style custom step temp press pxy v_vxy v_vxx
run 500000
variable eta equal v_v11
variable etaxy equal v_vxy
variable etaxx equal v_vxx
variable eta equal 0.5*(${etaxy}+${etaxx})
print "running average viscosity: ${eta}"