Fluctuating Inlet for DNS

ryanpewowaruk · March 7, 2019, 11:20

I am simulating a nozzle with a throat Re of 3500. I have the resources to directly resolve the jet breakdown after the nozzle but I need fluctuating inflow BCs to get physically realistic results.

I know there are fluctuating inflow BCs for LES but can't figure out how to use fluctuating inflow BCs when directly solving navier-stokes.

If anyone has suggestions I'd appreciate it.

Thanks in advance.

LuckyTran · March 7, 2019, 16:16

In DNS you have to directly specify the inflow, your fluctuating inlet BC is just a velocity inlet where you completely specify the velocity everywhere, all the time.

ryanpewowaruk · March 7, 2019, 19:24

Yes, I understand I need to specify inflow everywhere for all time. Using the built-in turbulence generation features from LES would be nice as otherwise I need to write my own udf.

March 7, 2019, 11:20	Fluctuating Inlet for DNS	#1
ryanpewowaruk New Member Wisconsin Join Date: Mar 2019 Posts: 2 Rep Power: 0	I am simulating a nozzle with a throat Re of 3500. I have the resources to directly resolve the jet breakdown after the nozzle but I need fluctuating inflow BCs to get physically realistic results. I know there are fluctuating inflow BCs for LES but can't figure out how to use fluctuating inflow BCs when directly solving navier-stokes. If anyone has suggestions I'd appreciate it. Thanks in advance.

March 7, 2019, 16:16		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,761 Rep Power: 66	In DNS you have to directly specify the inflow, your fluctuating inlet BC is just a velocity inlet where you completely specify the velocity everywhere, all the time. GaryPei likes this.

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March 7, 2019, 19:24		#3
ryanpewowaruk New Member Wisconsin Join Date: Mar 2019 Posts: 2 Rep Power: 0	Yes, I understand I need to specify inflow everywhere for all time. Using the built-in turbulence generation features from LES would be nice as otherwise I need to write my own udf.