|
From: | Georg Rempfer |
Subject: | Re: [ESPResSo-users] lbfluid GPU vs CPU |
Date: | Fri, 26 Jun 2015 13:57:26 +0200 |
How does the momentum field look?
How does it look with PBC and pressure driven flow?
On 25/06/15 14:08, Georg Rempfer wrote:
> If you look at the actual vector valued oscillations, what's the pattern?
> What happens if you increase the viscosity (say by a factor of two)?
> What happens when you set agrid=0.5?
> What happens when you change the time step?
>
> On Tue, Jun 23, 2015 at 2:22 PM, Markus Gusenbauer
> <address@hidden
--> <mailto:address@hidden>> wrote:
>
> Hi,
>
> there is an issue with lbfluid comparing GPU and CPU. I have a
> rectangular channel with wall velocity inflow from the left. With
> CPU the parabolic flow looks fine, but with GPU there is a standing
> wave (see pictures attached). I have a minimal working example below.
>
> What could be the problem? I tried version
> "ESPResSo-3.4-dev-172-g5e97dc1-dirty-git" and the latest master from
> today.
>
> Markus
>
>
>
>
> setmd time_step 1.0
> setmd skin 0.2
> thermostat off
>
> set boxX 30
> set boxY 10
> set boxZ 10
>
> setmd box_l $boxX $boxY $boxZ
>
> lbfluid cpu grid 1. dens 0.008 visc 0.032 tau 1.0 friction 0.5
>
> # fluid inflow
> lbboundary wall normal 1 0 0 dist 1 type 501 velocity 2.5e-4 0. 0.
>
> lbboundary wall normal 0 1 0 dist 1 type 501
> lbboundary wall normal 0 -1 0 dist [expr -$boxY+1] type 501
> lbboundary wall normal 0 0 1 dist 1 type 501
> lbboundary wall normal 0 0 -1 dist [expr -$boxZ+1] type 501
>
> ############################################################################
> # main iteration loop
> set cycle 0
> set endCycle 2000
>
> while { $cycle<$endCycle } {
> puts "$cycle"
> if { $cycle == 1999 } { lbfluid print vtk velocity "fluid.vtk" }
> integrate 10
> incr cycle
> }
>
>
>
>
>
Dr Ulf D Schiller
Centre for Computational Science
University College London
20 Gordon Street
London WC1H 0AJ
United Kingdom
Phone: +44 (0)20 7679 5300
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