August 2010 - Nek5000-users - mailman3.cels.anl.gov

Re: [Nek5000-users] Low Mach Number solver
by nek5000-users＠lists.mcs.anl.gov 11 Aug '10

11 Aug '10

Hi Stefan, Thanks for your reply. Regards, Pradeep > ---------- Forwarded message ---------- > From: nek5000-users(a)lists.mcs.anl.gov > To: <nek5000-users(a)lists.mcs.anl.gov> > Date: Tue, 10 Aug 2010 22:27:06 +0200 > Subject: Re: [Nek5000-users] Low Mach Number solver > Hi Pradeep, > > you'll find all details about the implemented Low Mach number algorithm in: > > A.G. Tomboulides, J.C.Y. Lee, and S.A. Orzag. Numerical Simulation of Low > Mach Number Reactive Flows. Journal of Scientific Computing, 1997:139–167, > 12. > > Only the thermodynamic pressure (p0) matters for the thermodynamic > properties (e.g. density). > p0 is constant in space, in fact the current implementation makes the > assumption that p0 is constant (open system). > > Please note that the prenek is quite outdated and does not support all new > features (e.g. Low Mach number formulation). We're working on more power > meshing options which will replace prenek at some point. > > hth, > Stefan > > > > On Aug 10, 2010, at 5:50 PM, <nek5000-users(a)lists.mcs.anl.gov> wrote: > > > Hi, > > > > I am new to Nek5000, and had a question regarding the Low Mach Number > solver. > > > > Does the Low Mach Number solver use an algorithm that splits pressure > into a time dependent, but spatially independent component ( > P_thermodynamic, used to calculate the density), and a spatially and time > dependent component? > > If so, what is the variable name for P_thermodynamic? > > > > If you use another algorithm, could you please point me to a paper that > explains it (if there is one). (The examples doc from the Nek5000 wiki > currently doesn't have this info.) > > > > I am asking this to be able to correctly set/calculate rho*cp (UTRANS) in > the uservp subroutine. > > > > Also, I am not directly able to enable the IFLOMACH option using prenek. > (I need to change it manually in the .rea file by replacing the existing > parameters with the ones from the lowMach_test example). I am currently > using the version 2.6099999 of Nekton and the version of prenek that came > with that. Is this something that will be implemented later? > > > > Thanks, > > Pradeep > > > > _______________________________________________ > > Nek5000-users mailing list > > Nek5000-users(a)lists.mcs.anl.gov > > https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users > > > > > ---------- Forwarded message ---------- > From: nek5000-users(a)lists.mcs.anl.gov > To: nek5000-users(a)lists.mcs.anl.gov > Date: Wed, 11 Aug 2010 08:03:01 -0500 (CDT) > Subject: Re: [Nek5000-users] Smooth Restart feature in Nek > > Shriram, > > Attached is a full-restart routine. You need to update the repo > to use it. It seems to work ok - hopefully the remarks in the attached > .usr file are clear. > > Paul > > On Mon, 9 Aug 2010, nek5000-users(a)lists.mcs.anl.gov wrote: > > Hi Paul, >> >> Thanks a lot. That would be very helpful. >> >> Regards >> Shriram >> > > _______________________________________________ > Nek5000-users mailing list > Nek5000-users(a)lists.mcs.anl.gov > https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users > > -- Pradeep C. Rao Graduate Research Assistant for FT2L (http://www1.mengr.tamu.edu/FT2L/) Department of Mechanical Engineering Texas A&M University College Station, TX 77843-3123 428 Engineering Physics Building (713) 210-9769

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Low Mach Number solver
by nek5000-users＠lists.mcs.anl.gov 10 Aug '10

10 Aug '10

Hi, I am new to Nek5000, and had a question regarding the Low Mach Number solver. Does the Low Mach Number solver use an algorithm that splits pressure into a time dependent, but spatially independent component ( P_thermodynamic, used to calculate the density), and a spatially and time dependent component? If so, what is the variable name for P_thermodynamic? If you use another algorithm, could you please point me to a paper that explains it (if there is one). (The examples doc from the Nek5000 wiki currently doesn't have this info.) I am asking this to be able to correctly set/calculate rho*cp (UTRANS) in the uservp subroutine. Also, I am not directly able to enable the IFLOMACH option using prenek. (I need to change it manually in the .rea file by replacing the existing parameters with the ones from the lowMach_test example). I am currently using the version 2.6099999 of Nekton and the version of prenek that came with that. Is this something that will be implemented later? Thanks, Pradeep

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Performance problem
by nek5000-users＠lists.mcs.anl.gov 06 Aug '10

06 Aug '10

Hi, I'm solving for Rayleigh-Benard convection in a 3D box of 37632, 4rth order elements. I fired the job on 512 processors on a machine with quad-core, quad socket configuration (32 nodes with 16 cores each ) with a 20 Gbps infiniband interconnect. In 12 hours it has run 163 time steps. Is this normal or is there maybe some way to improve performance? Attached is the SIZE file. Regards, Mani chandra

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Marangoni flow
by nek5000-users＠lists.mcs.anl.gov 05 Aug '10

05 Aug '10

Hello Paul, Just wondering if you have had some time to think about the issue of including the Marangoni stress in a two-fluid model. Cheers, Frank -- Frank Herbert Muldoon, Ph.D. Mechanical Engineering Technische Universität Wien (Vienna Technical University) Inst. f. Strömungsmechanik und Wärmeübertragung (Institute of Fluid Mechanics and Heat Transfer) Resselgasse 3 1040 Wien Tel: +4315880132232 Fax: +4315880132299 Cell:+436765203470 fmuldoo (skype) http://tetra.fluid.tuwien.ac.at/fmuldoo/public_html/webpage/frank-muldoon.h…

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Restart w/o saving over existing fld files?
by nek5000-users＠lists.mcs.anl.gov 05 Aug '10

05 Aug '10

Hello, Is there a way to restart without having Nek save new blah.f files over existing ones, perhaps tell it the number to start with? Say I have run a simulation and have 50 fld files. I would like to restart from 50, but the next fld ideally should read 51, not 1. This makes it difficult to get into visit I have found when doing restarts (unless there is alternative trick to get around this?) Thanks for any help with this , Michael

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Problem with the votex breakdown example
by nek5000-users＠lists.mcs.anl.gov 04 Aug '10

04 Aug '10

Hello， I ran the example case 'r1854' in \nek_svn\examples\escudier, and I didn't changed anything, then I loaded the reults in VIsit 2.0. There seems some problem with the mesh. The image is attached. The nek source is the latest. How does this come out？ By the way, how can I make similar cylindrical mesh, is there examples or detailed description? Regards Bofu Wang

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