Convergent divergent nozzle

csmistry · August 28, 2009, 04:30

Dear sir,

I am doind analysis of CD nozzle. with simple example with variation of pressures to study flow behaviour inside. also want to capture shock in it.. i took pressure 1 bar at inlet ,0.54 at outlet(critical pressure ratio). i am not getting convergence and after some convergence i am getting mass flow rate parameter along the center portion of geometry...

Weather my BC are wrong or my understading is wrong please guide me.

The CCL file,Mesh,convergence plot i am attaching here

ckleanth · August 28, 2009, 05:26

well maybe the simulation is transient?

have you read the faq and especialy the section for convergence?

csmistry · August 28, 2009, 06:27

no man please refer CCL>TXT ... analysis is steadystate

ckleanth · August 28, 2009, 06:48

i know you setup the simulation as a steady state.. but is it?

ghorrocks · August 28, 2009, 07:33

It may be transient but there are a lot of other things to check first. This question has been asked millions of times so here's my best guide as to how to proceed.
http://www.cfd-online.com/Wiki/Ansys...gence_criteria

kingjewel1 · August 29, 2009, 12:06

How do you know that's not a converged solution given your conditions?
What are your criteria?

Mehul157@yahoo.com · September 16, 2009, 02:40

Hi Mistry,

I think you will not get better convegence than you have achieved. It may be becuase you problem can be bestly described by LES.

Regards
Mehul

August 28, 2009, 05:26		#2
ckleanth Senior Member George Join Date: Mar 2009 Location: Birmingham, UK Posts: 257 Rep Power: 18	well maybe the simulation is transient? have you read the faq and especialy the section for convergence? __________________ Top 4 tips 1. Knowledge is everything and Ignorance is dangerous. 2. Understand your limitations and try to eliminate them. 3. Get yerself a bike and hoon the chuffer. You will soon learn why dogs like to hang their heads out the car window. 4. Please before asking any questions on how to run simulations in CFX, go though all the tutorials

August 28, 2009, 06:27	reply	#3
csmistry Member mistry Join Date: Apr 2009 Location: India Posts: 69 Rep Power: 17	no man please refer CCL>TXT ... analysis is steadystate

August 28, 2009, 06:48		#4
ckleanth Senior Member George Join Date: Mar 2009 Location: Birmingham, UK Posts: 257 Rep Power: 18	i know you setup the simulation as a steady state.. but is it? __________________ Top 4 tips 1. Knowledge is everything and Ignorance is dangerous. 2. Understand your limitations and try to eliminate them. 3. Get yerself a bike and hoon the chuffer. You will soon learn why dogs like to hang their heads out the car window. 4. Please before asking any questions on how to run simulations in CFX, go though all the tutorials

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August 28, 2009, 07:33		#5
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	It may be transient but there are a lot of other things to check first. This question has been asked millions of times so here's my best guide as to how to proceed. http://www.cfd-online.com/Wiki/Ansys...gence_criteria

August 29, 2009, 12:06		#6
kingjewel1 Senior Member Join Date: Jul 2009 Posts: 260 Rep Power: 18	How do you know that's not a converged solution given your conditions? What are your criteria?

September 16, 2009, 02:40		#7
Mehul157@yahoo.com New Member Mehul Join Date: Mar 2009 Posts: 6 Rep Power: 17	Hi Mistry, I think you will not get better convegence than you have achieved. It may be becuase you problem can be bestly described by LES. Regards Mehul