[lammps-users] temperature not constant

Hi Lammps,

I am simulating a flow with time dependent body force. I could manage to create sinusoidal body force using
the variable and jump commands. However the temperature of the system is gradually decreasing with time.
Here is part of my input script where I do this.

variable pi equal 3.14159265
variable tp equal 1000
variable alpha equal 0.005
variable con equal 2*{pi}/{tp}
variable neq equal 200000
variable navg equal 400000

reset_timestep 0
label loop
variable t loop {neq} variable f equal 0.05+{alpha}sin(${con}$t)
fix 4 flow addforce $f 0.0 0.0
run 1
unfix 4
next t
jump equil.in loop


I would debug your own script. Are you sure the addforce
command is getting the $f you expect (try printing it)? What
happens if you run a long time with a single $f? Etc.