Hi all users,
I need your help in the following problem:
I want to simulate a Poisseuille DPD flow. I create for that an upper, a lower
wall and a fluid domain. I run a first simulation with those conditions:
a)DPD pairstyle
b)lower wall with fcc lattice (dy=2.88, from -7.88 to 5.00)
c)upper wall with fcc lattice (dy=2.88, from 5.00 to 7.88)
d)fluid domain with sc lattice (dy=10.00, from -5.00 to 5.00)
e)flow nve
f)fix 1 lower temp/rescale 10 1.0 1.0 0.02 1.0 (thermostated lower wall)
g)fix 2 uppertemp/rescale 10 1.0 1.0 0.02 1.0 (thermostated upper wall)
h)Bounce-back conditions close to the walls
i)compute mobile all temp
velocity all create 1.0 482748 temp mobile units box,
for temperature and velocity calculation
j)use of fix ave/spatial for velocity, density, temperature and pressure
profile.
I then write a restart file for 100.000 time steps and read it in a second
simulation.The second simulation has the following conditions:
a)The same lattice spacings for both wall and fluid domain (these are redefined)
b)Spring in walls with constant 150 (use of fix spring/self command-units lj)
c)temp/rescale in walls (like those of the first simulation)
d)no velocity computation
By the use of fix ave/spatial command I can see that in the second simulation
there is no change for the prices of velocity, density, temperature and
stress/atom no matter what is the running step. For example for the velocity
profile:
timestep 100100:
24 -4.93446 1 1.1546 (for layer 24)
timestep 200000:
24 -4.93446 1 1.1546 (for layer 24)
My question is whether the velocity computation must be used for the second
simulation(althiugh i tried it and didn't get the right parabolic profile).Am I
doing something wrong with those conditions?Is there anything i should
change?Thanks very much in advance.
Dorothy
Phd student
University of Thessaly