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[ESPResSo-users] No rotation of an object into a couette-flow

From: Holst, Lena
Subject: [ESPResSo-users] No rotation of an object into a couette-flow
Date: Wed, 29 Jul 2015 07:58:31 +0000



I like to simulate an rigid object into influence of a couette-flow. The walls moves to opposite directions with an velocity of 0,3m/s. The object has an diameter of 0,4um and the walls a height of 40um. The density of the object is the same as the density of the fluid. The object is positioned in the middle of the channel. That should have the effect, that the object does not moves in one direction, it only should rotates. The object does not move, but it does not rotate, too. Before the same was simulated with another software. There the object began to rotate after 25us. In my simulation it does not rotate after 2ms.

I have a discretization of: dx=0,2um and dt=0,004us


I have run the simulation with an rigid object with virtual sites and another time with an OIF object, where I have choose the elastic parameters in this way, that the object is as much as possible rigid.

In both simulations I get the same: no rotation.


For better help there are the tcl-files for the simulations at the appendix and the text-files with the position of the object-particles.


Maybe there is miss any feature, that is to add. I have look at the UG, but have not found anything, that make sense.

If the discretization of dx=0,2um is too high, it would wonder me, because it is the same as in the simulation with the other software.

For an object with virtual sites I have calibrate mass and friction in the same way as for an OIF object.


I would be very thankful for help.


Kind regards,

Lena Holst


Fraunhofer ICT-IMM

Gruppe Modellierung / Modeling Group

Abteilung Zukunftstechnologien / Future Technologies Department

Carl-Zeiss-Stra├če 18-20, 55129 Mainz, Germany

Phone +49 6131 990-396 / Fax +49 6131 990-205 / Mobile +49 1577-5327027

address@hidden /


Attachment: Couette_VirtSites.tcl
Description: Couette_VirtSites.tcl

Attachment: Couette_FastStarr.tcl
Description: Couette_FastStarr.tcl

Attachment: Nodes_R1ExtremGrobUx150Uy100.5Uz20.txt
Description: Nodes_R1ExtremGrobUx150Uy100.5Uz20.txt

Attachment: sphere126nodes.dat
Description: sphere126nodes.dat

Attachment: sphere126triangles.dat
Description: sphere126triangles.dat

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