git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@10777 f3b2605a-c512-4ea7-a41b-209d697bcdaa

examples/VISCOSITY/in.mp.2d

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+# sample LAMMPS input script for viscosity of 2d LJ liquid
+# Muller-Plathe via fix viscosity
+
+# settings
+
+variable	x equal 20
+variable	y equal 20
+
+variable	rho equal 0.6
+variable        t equal 1.0
+variable	rc equal 2.5
+
+# problem setup
+
+units		lj
+dimension	2
+atom_style	atomic
+neigh_modify	delay 0 every 1
+
+lattice         sq2 ${rho}
+region          simbox block 0 $x 0 $y -0.1 0.1
+create_box      1 simbox
+create_atoms    1 box
+
+pair_style      lj/cut ${rc}
+pair_coeff      * * 1 1
+
+mass            * 1.0
+velocity        all create $t 97287
+
+fix             1 all nve
+fix	        2 all langevin $t $t 0.1 498094
+fix	        3 all enforce2d
+
+# equilibration run
+
+thermo          1000
+run	        5000
+
+unfix		2
+
+# turn on Muller-Plathe driving force and equilibrate some more
+
+velocity	all scale $t
+
+fix		4 all viscosity 100 x y 20
+fix		5 all ave/spatial 20 50 1000 y center 0.05 vx &
+		  units reduced file profile.mp.2d
+
+# equilibration run
+
+variable	dVx equal f_5[10][3]-f_5[1][3]
+
+thermo          1000
+thermo_style	custom step temp epair etotal press f_4 v_dVx
+run		20000
+
+# data gathering run
+# reset fix viscosity to zero flux accumulation
+
+unfix		4
+fix		4 all viscosity 100 x y 20
+
+variable	visc equal -(f_4/(2*(step*0.005-125)*lx+1.0e-10))/(v_dVx/(ly/2))
+fix		vave all ave/time 1000 1 1000 v_visc ave running start 26000
+
+thermo_style	custom step temp f_4 v_dVx v_visc f_vave
+
+#dump	        1 all custom 100 dump.mp.2d id type x y z vx
+
+run	        50000