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Re: [ESPResSo-users] About electrohydrodynamics
From: |
Stefan Kesselheim |
Subject: |
Re: [ESPResSo-users] About electrohydrodynamics |
Date: |
Wed, 31 Aug 2011 06:43:56 +0200 |
Hi.
Am 30.08.2011 um 23:46 schrieb Chunda Zhou:
> Hi Guys,
> My system is a polyelectrolete chain in salt solution with external electric
> field.
>
> From the users guide, one can assign an overall electric field. setmd mu_E
> μEx μEy μEz. Does it mean, this simply assigned the velocity of the charged
> objects? If yes, then assume I have two charged particles under the external
> field. In this case, is the velocity of each particle a function of μE or a
> function of μE and the electric field of the other particle?
The first: There is no concept of external electric fields in espresso, and
thus the input quantity mu E determines the velocity that a particle will have
at the end of the day. That is why we called that quantity muE because it
supposed to be the product of the two :-).
>
> In the literature [19], F-ξ(v-μE)=0. ξ is drag coefficient. Is there a way to
> assign different drag coefficients for different objects? Or all the objects
> share the same coefficient which is one?
The drag coefficient is the lattice-boltzmann friction coefficient, given in
the command.
lbfluid [...] friction $gamma
All particles have the same friction coefficient. To implement different
friction coefficients for different particles is a bit of work, but might be
desirable for the general usage of LB in general, too, and thus should be
implement in a general way. If you need it, please contact me.
If you have any more trouble with the implementation, please contact me, too.
We have tested it, and is not that complex, but I think you are one of the
first people to actually use it :-).
Cheers and good luck,
Stefan
>
> Best,
> Chunda
>
>
Stefan Kesselheim
Institute for Computational Physics
University of Stuttgart
address@hidden