Re: [ESPResSo-users] Lattice Boltzmann External Force

[Ulf Schiller]

On 02/11/2012 08:48 PM, Stefan Kesselheim wrote:
> Am 09.02.2012 um 14:28 schrieb Wolfgang Riefler:
>
> > Implementing this line, I get a much better result, with only a little offset, 
> > which is probably due to the discrete boundary.

It is a re-definition of the hydrodynamic velocity that has to be
applied when you measure the velocity. You take the first moment of the
populations and add a "look-ahead" for the force which can be seen as an
offset. The re-definition stems from the Chapman-Enskog expansion
including external forces. These forces are assumed to be velocity
independent, otherwise an implicit integration scheme would be needed to
make the forces self-consistent.

Thanks to Wolfgang for pointing this out!

Best wishes,
Ulf

--
Dr. Ulf D. Schiller                        Building 04.16, Room 3006
Institute of Complex Systems (ICS-2)       Phone:   +49 2461 61-6144
Forschungszentrum Jülich, Germany          Fax:     +49 2461 61-3180

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