MaxCo for airfoil simulation

rfiore1 · November 26, 2019, 08:00

Goodmorning to everyone,

I am doing a simulation of an airfoil in 2D with a Re = 30000 and I have some problems regarding the maxCo because Initially I have set this value around 20 but when I have reduced this value to 10 I have noticed that the solution is very different. I am using a pimpleFoam solver.

Is there a general rule to impose the maxCo value?
thanks

HPE · November 28, 2019, 17:46

rans, des or les?
please consider to read the forum's guidelines for questions, so that the community can try to help you.

Bazinga · November 29, 2019, 01:09

I assume you are talking about the Courant number. Yes, you might need a Courant number of < 1. This way a the fluid does not travel further than your cells within one time step. That is explained in most text books. This is also called the CFL (Courant-Friedrichs-Lewy) condition.

November 26, 2019, 08:00	MaxCo for airfoil simulation	#1
rfiore1 New Member Raffaele Join Date: Oct 2019 Posts: 3 Rep Power: 7	Goodmorning to everyone, I am doing a simulation of an airfoil in 2D with a Re = 30000 and I have some problems regarding the maxCo because Initially I have set this value around 20 but when I have reduced this value to 10 I have noticed that the solution is very different. I am using a pimpleFoam solver. Is there a general rule to impose the maxCo value? thanks

November 28, 2019, 17:46		#2
HPE Senior Member Herpes Free Engineer Join Date: Sep 2019 Location: The Home Under The Ground with the Lost Boys Posts: 931 Rep Power: 13	rans, des or les? please consider to read the forum's guidelines for questions, so that the community can try to help you. __________________ The OpenFOAM community is the biggest contributor to OpenFOAM: User guide/Wiki-1/Wiki-2/Code guide/Code Wiki/Journal Nilsson/Guerrero/Holzinger/Holzmann/Nagy/Santos/Nozaki/Jasak/Primer Governance Bugs/Features: OpenFOAM (ESI-OpenCFD-Trademark) Bugs/Features: FOAM-Extend (Wikki-FSB) Bugs: OpenFOAM.org How to create a MWE New: Forkable OpenFOAM mirror

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November 29, 2019, 01:09		#3
Bazinga Senior Member Join Date: Jun 2012 Location: Germany, Bochum Posts: 230 Rep Power: 16	I assume you are talking about the Courant number. Yes, you might need a Courant number of < 1. This way a the fluid does not travel further than your cells within one time step. That is explained in most text books. This is also called the CFL (Courant-Friedrichs-Lewy) condition.