dynLagrangian LES simulation diverges

Lorenzo92 · September 3, 2016, 06:39

Hello everyone,

I am getting trouble with an incompressible LES simulation performed with the dynLagrangian LESModel. The calculation indeed diverges.
I'll briefly describe my setup for the sake of clarity:

inlet/outlet patch : pressureInletOutletVelocity bc on U
total pressure with p0 uniform -20.5 bc on p

wall patch : fixedValue (0,0,0) bc on U
zeroGradient bc on p

throat patch : zeroGradient bc on U
totalPressure with p0 uniform -20.5 bc on p.

The throat patch , according to the imposed value of total Pressure, drives the behaviour of this patch as an inlet or an outlet

My major problems, for which I ask your help, are two :

1) which boundary conditions and initial conditions do I have to assign to flm and fmm using the dynLagrangian model?

2) Currently I used zeroGradient for both flm and fmm everywhere apart from the throat patch where I imposed fixed value. This setup was also suggested in previous threads : http://www.cfd-online.com/Forums/ope...dynlagrangian- sgs-model.html.
The fact is that flm simply explodes causing divergenge of Cs = flm/fmm and nuSGS consequently , a fact which is reported also by a user in the above quoted thread.
How to overcome this issue in your opinion?

Additionally my version of OF in 2.4.0.
I'll wait for any suggestions, maybe of users who had more experience than me with this LESModel. Thanks!

Lorenzo92 · September 12, 2016, 13:12

Nobody did ever manage to run a simulation on complex geometry with this model (not channel flow with cyclic bc )?

September 3, 2016, 06:39	dynLagrangian LES simulation diverges	#1
Lorenzo92 Member Lorenzo Join Date: Oct 2015 Location: Graz Posts: 49 Rep Power: 10	Hello everyone, I am getting trouble with an incompressible LES simulation performed with the dynLagrangian LESModel. The calculation indeed diverges. I'll briefly describe my setup for the sake of clarity: inlet/outlet patch : pressureInletOutletVelocity bc on U total pressure with p0 uniform -20.5 bc on p wall patch : fixedValue (0,0,0) bc on U zeroGradient bc on p throat patch : zeroGradient bc on U totalPressure with p0 uniform -20.5 bc on p. The throat patch , according to the imposed value of total Pressure, drives the behaviour of this patch as an inlet or an outlet My major problems, for which I ask your help, are two : 1) which boundary conditions and initial conditions do I have to assign to flm and fmm using the dynLagrangian model? 2) Currently I used zeroGradient for both flm and fmm everywhere apart from the throat patch where I imposed fixed value. This setup was also suggested in previous threads : http://www.cfd-online.com/Forums/ope...dynlagrangian- sgs-model.html. The fact is that flm simply explodes causing divergenge of Cs = flm/fmm and nuSGS consequently , a fact which is reported also by a user in the above quoted thread. How to overcome this issue in your opinion? Additionally my version of OF in 2.4.0. I'll wait for any suggestions, maybe of users who had more experience than me with this LESModel. Thanks!

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September 12, 2016, 13:12		#2
Lorenzo92 Member Lorenzo Join Date: Oct 2015 Location: Graz Posts: 49 Rep Power: 10	Nobody did ever manage to run a simulation on complex geometry with this model (not channel flow with cyclic bc )?