CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM Running, Solving & CFD (http://www.cfd-online.com/Forums/openfoam-solving/)
-   -   Does laminar mean DNS? (http://www.cfd-online.com/Forums/openfoam-solving/116520-does-laminar-mean-dns.html)

kkpal April 21, 2013 11:13

Does laminar mean DNS?
 
HI everyone!
I'm doing flow around cylinder at Re=100, and I chose laminar as the RASModel in RASproperties file. Dose it mean the simulation is running in Direct numerical simulation?

Lieven April 21, 2013 17:11

That is indeed what it means, pretty cool he ;-).

But note that if the flow is turbulent, a very fine mesh is required to get an accurate result. This is in fact already the case for you (you can check the discussion on the flow regimes at http://en.wikipedia.org/wiki/Reynolds_number ). So to get accurate results for the Re = 100, you should:
* run in 3D
* do a transient simulation
* perform a grid sensitivity study (to find the required number of cells)

If any of the above is not achievable, you should keep Re < 40 in which case the flow should be laminar so that a 2D, steady state, crude mesh simulation should be acceptable (if it is an infinite cylinder). Note however that even in this case turbulent structures might appear due to numerical inaccuracies.

Cheers,

L


All times are GMT -4. The time now is 21:51.