Problem in simulation

CHAYANIT · May 27, 2018, 07:27

I did simulation on an airfoil .Initially upto 0.2 seconds it ran perfectly but after that the simulation stopped because the courant number increases far above 1.Why might be the reason of courant number increase??

sktsang · May 27, 2018, 23:29

I also have similar problem. What I was modeling were intake manifolds for car engines. I use 3d mesh, with tetrahedral elements and penta elements for boundary layers, and triangle and quadrilateral shell meshes for walls and openings. When I start the simulation OpenFOAM already reported max Courant Number something like 20 or even 373 (!) (min Courant number around 0.1 looks ok). The calculation blows up very soon. I have tried remeshing the model but it's still the same.

What is funny is that the same 3d mesh does not have problems in Abaqus CFD run, in Abaqus CFD it just run perfectly no matter I use Spalart or k epsilon model although it takes a bit longer time (I keep the default 0.45 Courant number as what Abaqus suggested).

I have read the other sources online, on setting the nCorrectors, nOuterCorrectors, whatever, but it still keep on blowing up very soon. OpenFOAM is strange to me ...

May 27, 2018, 07:27	Problem in simulation	#1
CHAYANIT New Member Chayanit Nigaltia Join Date: Jan 2018 Posts: 29 Rep Power: 8	I did simulation on an airfoil .Initially upto 0.2 seconds it ran perfectly but after that the simulation stopped because the courant number increases far above 1.Why might be the reason of courant number increase??

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May 27, 2018, 23:29		#2
sktsang New Member Join Date: May 2018 Posts: 3 Rep Power: 8	I also have similar problem. What I was modeling were intake manifolds for car engines. I use 3d mesh, with tetrahedral elements and penta elements for boundary layers, and triangle and quadrilateral shell meshes for walls and openings. When I start the simulation OpenFOAM already reported max Courant Number something like 20 or even 373 (!) (min Courant number around 0.1 looks ok). The calculation blows up very soon. I have tried remeshing the model but it's still the same. What is funny is that the same 3d mesh does not have problems in Abaqus CFD run, in Abaqus CFD it just run perfectly no matter I use Spalart or k epsilon model although it takes a bit longer time (I keep the default 0.45 Courant number as what Abaqus suggested). I have read the other sources online, on setting the nCorrectors, nOuterCorrectors, whatever, but it still keep on blowing up very soon. OpenFOAM is strange to me ...