Re: [ESPResSo-users] Espressomd-users Digest, Vol 55, Issue 11

[Holst, Lena]

Hi Ivan,

thank you for the answer. Do you know if there are samples, that shows how to 
create a sphere with virtual sites in espresso?

Thank you,

Lena Holst
_________________________________________________________ 
Fraunhofer ICT-IMM
Gruppe Modellierung / Modeling Group
Abteilung Zukunftstechnologien / Future Technologies Department
Carl-Zeiss-Straße 18-20, 55129 Mainz, Germany
Phone +49 6131 990-396 / Fax +49 6131 990-205 / Mobile +49 1577-5327027
address@hidden / www.imm.fraunhofer.de

-----Ursprüngliche Nachricht-----
Von: address@hidden [mailto:address@hidden Im Auftrag von address@hidden
Gesendet: Mittwoch, 27. Mai 2015 08:31
An: address@hidden
Betreff: Espressomd-users Digest, Vol 55, Issue 11

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Contents of Espressomd-users digest..."


Today's Topics:

   1. Re: fixing an object in a fluid than only rotates (Ivan Cimrak)
   2. Re: fixing an object in a fluid than only rotates (Owen Hickey)
   3. Increase the lattice boltzmann agrid but got error. (Joe Ada)
   4. I have got a warning: Recalculating forces (Joe Ada)
   5. Re: I have got a warning: Recalculating forces (Wink, Markus)


----------------------------------------------------------------------

Message: 1
Date: Tue, 26 May 2015 21:38:19 +0200
From: Ivan Cimrak <address@hidden>
To: "address@hidden" <address@hidden>
Subject: Re: [ESPResSo-users] fixing an object in a fluid than only
        rotates
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset=UTF-8

Dear Lena,

Currently, there is no such functionality. Also, I can't see right now any way 
how to keeps let's say a centroid of the object fixed. The option of moving the 
centroid of the object always back is of course possible, but this way, you get 
the recalculating the forces, because the positions of the particles are being 
set.

If you want to simulate rigid objects, virtual sites are maybe an option, 
however, this is not within the OIF module.

I wonder what is the reason to have such feature. If you want to simulate 
couette flow and you want your object to be almost at one place, just with 
rotation, initiate the couette flow by moving the upper wall to the right and 
bottom wall to the left, both with halved velocities.

I hope this helps,
Ivan




D?a 26.5.2015 o 15:32 Holst, Lena nap?sal(a):
> Hello,
>
> I want to create an sphere object in a couette-flow. The object should 
> only be able to rotate, but fixed at one position. When I set the 
> origin of the object at each integrationstep at the same position, 
> every integration it comes the message ?Recalculated forces, so the LB 
> coupling forces are not included in the particle force the first time 
> step.? So, I think this way is not very useful. Is there any other way 
> to fix the object at one defined position, so that this is only able 
> to rotate through the force of the fluid?
>
> Best regards and a lot of thanks for effort,
>
> Lena Holst
>
> _________________________________________________________
>
> Fraunhofer ICT-IMM
>
> Gruppe Modellierung / Modeling Group
>
> Abteilung Zukunftstechnologien / Future Technologies Department
>
> Carl-Zeiss-Stra?e 18-20, 55129 Mainz, Germany
>
> Phone +49 6131 990-396/ Fax +49 6131 990-205 / Mobile +49 1577-5327027
>
> address@hidden / www.imm.fraunhofer.de
>

--
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



------------------------------

Message: 2
Date: Tue, 26 May 2015 23:01:58 +0200
From: Owen Hickey <address@hidden>
To: Ivan Cimrak <address@hidden>
Cc: "address@hidden" <address@hidden>
Subject: Re: [ESPResSo-users] fixing an object in a fluid than only
        rotates
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset=UTF-8

Hey all,

I think the easiest solution if you still want to use OIF is to simply
use the reuse_forces flag when calling integrate since the old forces
should still be correct in this case. Another option might be the COM
Virtual Sites, although I must concede I have no idea if it would
work.

Owen


On Tue, May 26, 2015 at 9:38 PM, Ivan Cimrak <address@hidden> wrote:
> Dear Lena,
>
> Currently, there is no such functionality. Also, I can't see right now
> any way how to keeps let's say a centroid of the object fixed. The
> option of moving the centroid of the object always back is of course
> possible, but this way, you get the recalculating the forces, because
> the positions of the particles are being set.
>
> If you want to simulate rigid objects, virtual sites are maybe an
> option, however, this is not within the OIF module.
>
> I wonder what is the reason to have such feature. If you want to
> simulate couette flow and you want your object to be almost at one
> place, just with rotation, initiate the couette flow by moving the
> upper wall to the right and bottom wall to the left, both with halved
> velocities.
>
> I hope this helps,
> Ivan
>
>
>
>
> D?a 26.5.2015 o 15:32 Holst, Lena nap?sal(a):
>> Hello,
>>
>> I want to create an sphere object in a couette-flow. The object should
>> only be able to rotate, but fixed at one position. When I set the origin
>> of the object at each integrationstep at the same position, every
>> integration it comes the message ?Recalculated forces, so the LB
>> coupling forces are not included in the particle force the first time
>> step.? So, I think this way is not very useful. Is there any other way
>> to fix the object at one defined position, so that this is only able to
>> rotate through the force of the fluid?
>>
>> Best regards and a lot of thanks for effort,
>>
>> Lena Holst
>>
>> _________________________________________________________
>>
>> Fraunhofer ICT-IMM
>>
>> Gruppe Modellierung / Modeling Group
>>
>> Abteilung Zukunftstechnologien / Future Technologies Department
>>
>> Carl-Zeiss-Stra?e 18-20, 55129 Mainz, Germany
>>
>> Phone +49 6131 990-396/ Fax +49 6131 990-205 / Mobile +49 1577-5327027
>>
>> address@hidden / www.imm.fraunhofer.de
>>
>
> --
> 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
>



------------------------------

Message: 3
Date: Tue, 26 May 2015 21:30:20 -0400
From: Joe Ada <address@hidden>
To: ESPResSo Users <address@hidden>
Subject: [ESPResSo-users] Increase the lattice boltzmann agrid but got
        error.
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset="utf-8"

Hi Guys,

I found that when I increase the agrid of LB fluidics, without changing
anything else, I got the following error:
Complex value is not zero (i=16774,data=1.00968e-05)!!!

I wanted to increase the size of the simulation cube. Because of the limit
of memory, I can only increase agrid. Is there a upper limit of it?

Joe
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Message: 4
Date: Tue, 26 May 2015 21:51:28 -0400
From: Joe Ada <address@hidden>
To: ESPResSo Users <address@hidden>
Subject: [ESPResSo-users] I have got a warning: Recalculating forces
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset="utf-8"

I keep getting this warning from each iteration of the simulation, does
that mean my LB is not functional or some parameter of LB fluids is set
wrong?

*Warning: Recalculating forces, so the LB coupling forces are not included
in the particle force the first time step. This only matters if it happens
frequently during sampling.*

Thanks,
Joe
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Message: 5
Date: Wed, 27 May 2015 06:31:14 +0000
From: "Wink, Markus" <address@hidden>
To: "'Joe Ada'" <address@hidden>, ESPResSo Users
        <address@hidden>
Subject: Re: [ESPResSo-users] I have got a warning: Recalculating
        forces
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset="utf-8"

Hello Joe,

I didn?t really get it: do you get this message in every integration step, or 
just in the first one?
If it is in only in the first integration step, Owen gave a good explanation on 
the mailing list quite recently:

http://lists.nongnu.org/archive/html/espressomd-users/2015-05/msg00007.html


Cheers,

Markus


Von: address@hidden [mailto:address@hidden Im Auftrag von Joe Ada
Gesendet: Mittwoch, 27. Mai 2015 03:51
An: ESPResSo Users
Betreff: [ESPResSo-users] I have got a warning: Recalculating forces

I keep getting this warning from each iteration of the simulation, does that 
mean my LB is not functional or some parameter of LB fluids is set wrong?

Warning: Recalculating forces, so the LB coupling forces are not included in 
the particle force the first time step. This only matters if it happens 
frequently during sampling.
Thanks,
Joe
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