Large Eddy Simulation

ad6556s · February 12, 2016, 08:52

Hey Friends!
Does it make sence to do an LES in a high pressure flow (ideal gas, no constant density)? The aim is to find the detached point of the flow. The flow occurs in sub-, sonic and supersonic flow on an exhaust valve.

Thank You!

jesjes · February 12, 2016, 13:32

Typically LES isn't good at predicting flow separation. A better choice might be a detached eddy simulation (DES), which will treat near-wall regions in a RANS-like fashion (as the CFD Online wiki outlines).

LuckyTran · February 18, 2016, 07:54

I don't agree that DES will do any better than LES. DES is LES with more models.

I'm not sure what you expect to get from the LES when simpler RANS models will give similar insight. What LES gives you is a time-accurate solution with less modelling than RANS/URANS (more accurate turbulence). Unless you are interested in studying the turbulence itself, there's no reason to do LES over a simpler model.

February 12, 2016, 08:52	Large Eddy Simulation	#1
ad6556s New Member Deutschland Join Date: Jan 2016 Posts: 4 Rep Power: 10	Hey Friends! Does it make sence to do an LES in a high pressure flow (ideal gas, no constant density)? The aim is to find the detached point of the flow. The flow occurs in sub-, sonic and supersonic flow on an exhaust valve. Thank You!

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February 12, 2016, 13:32		#2
jesjes New Member Jesse Dumas Join Date: Aug 2013 Posts: 1 Rep Power: 0	Typically LES isn't good at predicting flow separation. A better choice might be a detached eddy simulation (DES), which will treat near-wall regions in a RANS-like fashion (as the CFD Online wiki outlines).

February 18, 2016, 07:54		#3
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 65	I don't agree that DES will do any better than LES. DES is LES with more models. I'm not sure what you expect to get from the LES when simpler RANS models will give similar insight. What LES gives you is a time-accurate solution with less modelling than RANS/URANS (more accurate turbulence). Unless you are interested in studying the turbulence itself, there's no reason to do LES over a simpler model.