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June 19, 2013, 04:21 |
icofoam = DNS?
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#1 |
Senior Member
Dongyue Li
Join Date: Jun 2012
Location: Beijing, China
Posts: 844
Rep Power: 18 |
hey guys,
In OpenFOAM, icofoam solve N-S equations with no additional models, AFAIK, its the same with DNS, so can I use icoFoam to simulate turbulence? Just by set delta t is very small such as:1e-7? Thanks. |
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July 2, 2013, 23:05 |
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#2 |
Senior Member
Santiago Marquez Damian
Join Date: Aug 2009
Location: Santa Fe, Santa Fe, Argentina
Posts: 452
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__________________
Santiago MÁRQUEZ DAMIÁN, Ph.D. Research Scientist Research Center for Computational Methods (CIMEC) - CONICET/UNL Tel: 54-342-4511594 Int. 7032 Colectora Ruta Nac. 168 / Paraje El Pozo (3000) Santa Fe - Argentina. http://www.cimec.org.ar |
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July 8, 2013, 23:33 |
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#3 | |
Senior Member
Dongyue Li
Join Date: Jun 2012
Location: Beijing, China
Posts: 844
Rep Power: 18 |
Quote:
I know there is a dnsFoam, but to my experience and Versteeg's book page 110: Code:
The instantaneous continuity and Navier–Stokes equations (3.23) and (3.24a–c) for an incompressible turbulent flow form a closed set of four equations with four unknowns u, v, w and p. Direct numerical simulation (DNS) of turbulent flow takes this set of equations as a starting point and develops a transient solution on a sufficiently fine spatial mesh with sufficiently small time steps to resolve even the smallest turbulent eddies and the fastest fluctuations. Anyway Im not familar with dnsDoam. Thanks. |
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July 9, 2013, 00:04 |
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#4 |
Senior Member
Santiago Marquez Damian
Join Date: Aug 2009
Location: Santa Fe, Santa Fe, Argentina
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If you check the code for dnsFoam you will see that it is similar to icoFoam, except for a source term which adds turbulence to the system. Without it the problem would evolve to a resting system due the dissipative effect of the viscosity.
Regards
__________________
Santiago MÁRQUEZ DAMIÁN, Ph.D. Research Scientist Research Center for Computational Methods (CIMEC) - CONICET/UNL Tel: 54-342-4511594 Int. 7032 Colectora Ruta Nac. 168 / Paraje El Pozo (3000) Santa Fe - Argentina. http://www.cimec.org.ar |
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February 1, 2014, 19:18 |
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#5 | |
Member
Join Date: Feb 2012
Posts: 49
Rep Power: 14 |
Quote:
1)should we except same result if we solve a laminar case by icoFoam and dnsFoam?Does that extra source term influences on the result for a laminar case? 2)Is there any difference between the cost of dnsFoam and icoFoam for a identical laminar test case? for example that extra source term might decrease the cost or not...? Thanks in advance |
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March 7, 2014, 22:48 |
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#6 |
Senior Member
Santiago Marquez Damian
Join Date: Aug 2009
Location: Santa Fe, Santa Fe, Argentina
Posts: 452
Rep Power: 24 |
Hi,
1) It depends on the relative intensity of the source term, but in general, yes. 2) They are the same solvers, the source terms add a little more cost. Regards
__________________
Santiago MÁRQUEZ DAMIÁN, Ph.D. Research Scientist Research Center for Computational Methods (CIMEC) - CONICET/UNL Tel: 54-342-4511594 Int. 7032 Colectora Ruta Nac. 168 / Paraje El Pozo (3000) Santa Fe - Argentina. http://www.cimec.org.ar |
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March 17, 2014, 06:08 |
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#7 | |
Senior Member
Huang Xianbei
Join Date: Sep 2013
Location: Yangzhou,China
Posts: 302
Rep Power: 14 |
Quote:
Ichecked the DNS solver and found a force add to the r.h.s of the UEqn, and find the definition: Code:
volVectorField force ( U/dimensionedScalar("dt", dimTime, runTime.deltaTValue()) ); I've looked into someone's code in this forum about channel flow DNS, the 'force' is not added, so I'd like to know is it necessary to do so? |
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June 8, 2014, 05:01 |
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#8 |
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Florian Ries
Join Date: Feb 2014
Location: Darmstadt, Germany
Posts: 88
Rep Power: 12 |
Hi,
in the description of dnsFoam.c you can find: Application dnsFoam Description Direct numerical simulation solver for boxes of isotropic turbulence In my opinion you only need this force, if you don't have shear or a wall that gives you shear. So dnsFoam is proper for the boxturb16 and for no other case. In the tutorial of Martin de Mare, he mentioned that the force term is to keep the turbulence alive. You only need this force, if you have no shear of e.g.shear at a wall? Because if you have a wall, turbulence keep alive by the shear, right? I want to simulate a quasi-DNS of pipeflow. From the description, dnsFoam solver is for DNS of isotropic turbulence in boxes. So this solver is not suitable for my case. Now my question: Is icoFoam the right solver for DNS in complex geometries with shear at a wall?? kind regards Florian |
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April 3, 2021, 23:28 |
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#9 |
New Member
Nidal
Join Date: Nov 2018
Posts: 17
Rep Power: 7 |
Hi, have you figured this out yet? As I have a similar problem to solve and Im not sure whether I can use icofoam for such a case.
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