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<body class='hmmessage'><div style="text-align: left;"><br></div><br><br><br><hr id="stopSpelling">> Date: Wed, 23 Apr 2008 05:29:26 -0700<br>> From: schneemilch@yahoo.com<br>> Subject: RE: [gmx-users] couette flow<br>> To: gmx3@hotmail.com<br>> <br>> <br>> <br>> <br>> --- On Wed, 4/23/08, Berk Hess <gmx3@hotmail.com> wrote:<br>> <br>> > From: Berk Hess <gmx3@hotmail.com><br>> > Subject: RE: [gmx-users] couette flow<br>> > To: schneemilch@yahoo.com<br>> > Date: Wednesday, April 23, 2008, 7:27 PM<br>> > > Date: Wed, 23 Apr 2008 02:34:49 -0700<br>> > > From: schneemilch@yahoo.com<br>> > > To: gmx-users@gromacs.org<br>> > > Subject: [gmx-users] couette flow<br>> > > <br>> > > Hi,<br>> > > Has anyone here used gromacs to simulate couette flows<br>> > in slit pores? I can see that it would be possible to use<br>> > the pull code but I would like to be able to run in<br>> > parallel. Any tips before I begin modifying source code<br>> > would be greatly appreciated.<br>> > > <br>> > > Cheers, Matt<br>> > <br>> > I don't see what this has to do with the pull code. The<br>> > pull code is made for forces between<br>> > centers of mass of groups.<br>> > <br>> > There are already some external force options in the mdp<br>> > file.<br>> > <br>> > But I don't see how you would set up an unbiased<br>> > couette flow.<br>> > In reality the flow is generated by a pressure difference.<br>> > In a simulation you can apply an external force or impose a<br>> > velocity profile.<br>> > But both these options make presumptions about the<br>> > force/flow profile.<br>> > <br>> > Berk.<br>> > <br>> <br>> Couette flow is shear driven, all you need is to have one pore wall moving relative to the other. I figure this could be done using the pull code by assigning each wall to a different group and using the pull code to increase the lateral distance between them at a constant rate. But it seems that the pull code does not work in parallel. Is there another way to prescribe the motion of one of the walls?<br>> Cheers, Matt<br><br>Ah, sorry, I confused it with Poiseuille.<br><br>The deform option does shear boundary conditions.<br><br>But if you want to move real walls, there is currently no simple option that gives<br>a group a constant velocity. The pull code should indeed do it. In the CVS version<br>the pull code also works in parallel.<br><br>BTW the reply address in your mail is your own address, instead of gmx-users,<br>I don't you if you caused this, or if something is wrong on the server.<br><br>Berk.<br><br><br><br /><hr />Express yourself instantly with MSN Messenger! <a href='http://clk.atdmt.com/AVE/go/onm00200471ave/direct/01/' target='_new'>MSN Messenger</a></body>
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