|
[Sponsors] |
October 14, 2006, 06:17 |
Hello,
I am running a LES t
|
#1 |
Member
anne dejoan
Join Date: Mar 2009
Location: madrid, spain
Posts: 66
Rep Power: 17 |
Hello,
I am running a LES to simulate the dispersion of a passive contamimant. I have tried linearLimited01 schemes for the scalar transport equation but I still have negative values. Could you please inform me about the best schemes available in OpenFoam to chose to ensure a positive scalar? Thanks You Anne |
|
October 14, 2006, 09:54 |
Use Gamma01 with the coefficie
|
#2 |
Senior Member
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,906
Rep Power: 33 |
Use Gamma01 with the coefficient of 0.5 or 1. You also need to limit the Laplace scheme for that scalar, e.g.
laplacian(DkEff,k) Gauss linear limited 1; On bad meshes you may need to use a lower coefficient, say 0.5 That should do it, Hrv
__________________
Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk |
|
October 14, 2006, 09:56 |
Forgot to say: temporal discre
|
#3 |
Senior Member
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,906
Rep Power: 33 |
Forgot to say: temporal discretisation may also give you unboundedness. A good way forward is Euler implicit (first order); if you really need second order you can try my new boundedBackward scheme.
Hrv
__________________
Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk |
|
October 16, 2006, 03:22 |
Dear Hrvoje,
Thank you,
|
#4 |
Member
anne dejoan
Join Date: Mar 2009
Location: madrid, spain
Posts: 66
Rep Power: 17 |
Dear Hrvoje,
Thank you, I will test your suggestions. Anne |
|
March 5, 2007, 05:10 |
I want to try different ddt-sc
|
#5 |
New Member
Per Nilsson
Join Date: Mar 2009
Location: Lund, Sweden
Posts: 21
Rep Power: 17 |
I want to try different ddt-schemes.
In order to see the choices I wrote "x": ------------------------------------------ Creating field DpDt --> FOAM FATAL IO ERROR : unknown ddt scheme x Valid ddt schemes are : 6 ( CoEuler boundedBackward CrankNicholson steadyState Euler backward ) file: /home/workdisc/OpenFOAM/pen-1.3/run/boundp3/system/fvSchemes::default at line 27. From function ddtScheme<type>::New(const fvMesh&, Istream&) in file /home/dm2/henry/OpenFOAM/OpenFOAM-1.3/src/finiteVolume/lnInclude/ddtScheme.C at line 80. FOAM exiting ------------------------------------------ When I try boundedBackward I get: ------------------------------------------ Creating field DpDt Starting time loop Time = 2e-06 Mean and max Courant Numbers = 0 0 diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0 --> FOAM FATAL IO ERROR : unknown ddt scheme boundedBackward Valid ddt schemes are : 5 ( CoEuler CrankNicholson steadyState Euler backward ) file: /home/workdisc/OpenFOAM/pen-1.3/run/boundp3/system/fvSchemes::default at line 27. From function ddtScheme<type>::New(const fvMesh&, Istream&) in file /home/dm2/henry/OpenFOAM/OpenFOAM-1.3/src/finiteVolume/lnInclude/ddtScheme.C at line 80. FOAM exiting ------------------------------------------ Why is boundedBackward no longer on the list? |
|
March 5, 2007, 05:34 |
Easy: a bounded backward schem
|
#6 |
Senior Member
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,906
Rep Power: 33 |
Easy: a bounded backward scheme I wrote is there for scalars only: you cannot define what "bounded" means in terms of a vector or a tensor. Therefore, I cannot define a bounded second-order scheme for a vector.
In order to do this well, you will need to specify a scheme on a per-ddt-term basis. Set default to none and the code will ask you for a scheme one ddt term at a time. Hrv
__________________
Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Low dissipation schemes for scalar transport | ivan_cozza | OpenFOAM Running, Solving & CFD | 0 | January 3, 2009 11:57 |
TVD-schemes | NewBee | Main CFD Forum | 4 | August 5, 2008 07:03 |
ENO schemes. | J. K | Main CFD Forum | 12 | June 28, 2002 11:16 |
TVD Schemes | Sudeep | FLUENT | 0 | October 14, 2000 21:31 |
TVD Schemes | Matt Umbel | Main CFD Forum | 1 | January 25, 2000 04:21 |