Re: [ESPResSo-users] Boundary condition and external force on electrokinetics fluid

[Georg Rempfer]

Hello Luam,

putting in the interface for the external LB force wouldn't be too much work. Switching out the periodic boundary conditions for something else unfortunately is. Out LB currently doesn't support flux boundary conditions and the electrostatics solver in electrokinetics uses FFTs and is inherently periodic.

Greetings,

Georg

2014-08-14 10:24 GMT+02:00 Luman Qu <address@hidden>:

Hi Georg,

Thank you so much for your reply. 

What I am interested in at moment is the density of charged species in a continuously running fluid under some external electric fields. To get the bulk fluid move, some external force or pressure should be applied, in my understanding. Therefore I asked the question. 

Also to simulate continuously running water, I don't think current periodic boundary condition suits this purpose, as the fluid enter the simulation box should be fresh (not the one that leaves the region).

Please correct me if I am wrong in any way. Thank you again for your kind help.

Sincerely,

Luman

On Thu, Aug 14, 2014 at 12:50 AM, Georg Rempfer <address@hidden> wrote:

Hey,

currently there is no interface for that feature. This is because initially we defined a separate electrokinetics species for the neutral fluid component as well and didn't implement the LB body force interface when we moved away from it. Are you interested in calculating streaming potentials?

Greetings,

Georg

2014-08-13 21:36 GMT+02:00 Luman Qu <address@hidden>:

Hi all,

I am exploring the newly-included Electrokinetics feature and have some questions. I would like to simulate continuous flow under external force (e.g. gravity).

1. According to the user guide, there is no option to apply an external force on the electrokinetic (EK) fluid. One can only apply electric force on the species in the EK fluid. Is there a way to apply an external force on the fluid itself (I believe it is possible for the lbfluid)?

2. I am a bit confused about the periodic boundary condition defined in the Espresso. Say if I want to simulate a continuous flow with two open ends (like a flow in a pipe), would the same fluid leaving from one end enter pipe again from the other end? Or it is the "fresh" fluid as initialized enter the pipe? 

Thank you so much in advance for any clarification.

Sincerely,

Luman