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-   -   How to change nu? (https://www.cfd-online.com/Forums/openfoam-solving/206452-how-change-nu.html)

fede32 September 6, 2018 23:51

How to change nu?
 
Hi, I want to decrease nu in a case where I have compute until a certain time, and then continue running with the new nu. I stop the running, let's say, at 5 sec, I change nu in constant/transportProperties, and then I run pimpleFoam again. But the solution does not change, so I assume that nu is not being changed. How can I effectively change it? How can I check the nu value assumed?

simrego September 7, 2018 02:46

Hi!


If I'm correct, pimpleFoam is using the singlePhaseTransportModel:
https://cpp.openfoam.org/v6/singlePh...8C_source.html
where the IOobject called "transportProperties" is a MUST_READ_IF_MODIFIED type, so you don't even have to stop the simulation.


What is the change? From what to what? And what if you have a big difference in the viscosity? Let's say one or two orders of magnitude? Then you must see some difference.

fede32 September 7, 2018 08:50

Quote:

Originally Posted by simrego (Post 705579)
Hi!


If I'm correct, pimpleFoam is using the singlePhaseTransportModel:
https://cpp.openfoam.org/v6/singlePh...8C_source.html
where the IOobject called "transportProperties" is a MUST_READ_IF_MODIFIED type, so you don't even have to stop the simulation.


What is the change? From what to what? And what if you have a big difference in the viscosity? Let's say one or two orders of magnitude? Then you must see some difference.


Thanks for your repply! The change I want to make is from nu=1e-03 to nu=1e-05.
I'm trying to do this because if I run with the real nu from the beginning, the simulation becomes unestable. (I'm calculating head loss in an elbow with k-epsilon)


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