Re: [ESPResSo-devel] shifted periodicity

[Axel Arnold]

Hi Ivan,

Take a look at the Lees-Edwards code in Espresso. That does time-dependent shifting, so is more complicated, but on the other hand has the necessary generalizations of parallel communication at least in one dimension. Is fairly tricky, though.

Best,

Axel

Axel Arnold

Martha-Schmidtmann-Str. 7

70374 Stuttgart, Germany

Email: address@hidden

Phone: +49 173 870 6659

Am 27.05.2015 um 22:37 schrieb Ivan Cimrak <address@hidden>:

Dear all,


Periodicity of the simulation box is implemented in a way that, e.g.
for the lbfluid, the following periodic condition is valid:
v(x, y, z) = v(x+boxX, y, z), similarly in other directions.

I need to implement shifted periodicity, something like this:
Let shiftY be a number between 0 and boxY indicating the shift in y
direction. The shifted periodicity condition would then be
v(x,y,z) = v(x+boxX, y + shiftY, z)
It could of course be even more complicated, with simultaneous shift
also in z direction, but for brevity let us keep it simple like above.


This shifted periodicity must of course be implemented also for
particles. Currently, two particles with very short-range interaction
(with cut_off e.g. 3*delta) feel each other in case their positions
are  e.g. (x+delta, y, z) and (x+boxX-delta, y,z). In case with
shifted periodicity, particles with these positions would not feel
each other, however, particles with positions (x+delta, y, z) a
(x+boxX-delta, y + shiftY,z) would do.


Can anyone give a reasonable estimate on how difficult it is to
implement something like this? And also, where in the code to look:-)

Thank you,
Ivan




--
Ivan Cimrak
FRI Zilinska Univerzita v Ziline
personal web: http://www.kst.fri.uniza.sk/~icimrak/
cell-in-fluid group: http://cell-in-fluid.fri.uniza.sk