EGR mixing case

rajeev50588 · February 26, 2013, 06:17

Hiii..
In this case i am simulating air and EGR mixing in this nozzle.
i am not willing to give mass flow inlet for EGR (although i have mass flow rates for EGR1 and EGR2 inlets). I want to drive the EGR due to pressure difference in this convergent divergent nozzle.
I have attached the BC's i want to simulate. Would like you to help me with the what exact BC's to be used. If i give mass flow then pressure dsnt matches and vice versa.I have used the following BC's but of no use
a) Inlet - Mass flow , EGR's inlet - stagnation inlet, Outlet - Pressure outlet
b) Inlet - Stagnation inlet, EGR's inlet - Pressure outlet ( with target mass flow) , Outlet - pressure outlet

Physics i have used are as follows:
Ideal gas, K-e turbulence, passive scalars, segregated temp, segregated energy, all y+ etc

Help me out with this

Regards
RD
egr case1.JPG

siara817 · February 26, 2013, 06:32

Have you tried to use pressure outlet for both inlet and outlet?

rajeev50588 · February 26, 2013, 06:45

yes i have done that too...i have mentioned the specified pressure given in the attachmnt for EGR inlet also along with this i have tried the target mass flow rate but of no use...m not getting the results as such

2pashtet · February 14, 2014, 13:20

Hi,
I have the same problem, I need to set pressure + masss flow inlet and pressure outlet.

I try:
1) Inlet - Stagnation pressure (16 atm)
Outlet - mass flow rate
I get solution, where i have the same total pressure on the whole computational domain, it's wrong result
2) Inltet - Pressure outlet (16 atm)
Outlet - Pressure outlet (0 atm) with target mass flow rate
I get solution with wrong mass flow rate

Help me please with advise
Regards
Paul

me3840 · February 14, 2014, 16:03

IMO the target mass flow option is not very good in STAR-CCM+, you can get better results by coding in the BC using Newton's method in Java.

February 26, 2013, 06:17	EGR mixing case	#1
rajeev50588 New Member Join Date: Feb 2013 Posts: 10 Rep Power: 13	Hiii.. In this case i am simulating air and EGR mixing in this nozzle. i am not willing to give mass flow inlet for EGR (although i have mass flow rates for EGR1 and EGR2 inlets). I want to drive the EGR due to pressure difference in this convergent divergent nozzle. I have attached the BC's i want to simulate. Would like you to help me with the what exact BC's to be used. If i give mass flow then pressure dsnt matches and vice versa.I have used the following BC's but of no use a) Inlet - Mass flow , EGR's inlet - stagnation inlet, Outlet - Pressure outlet b) Inlet - Stagnation inlet, EGR's inlet - Pressure outlet ( with target mass flow) , Outlet - pressure outlet Physics i have used are as follows: Ideal gas, K-e turbulence, passive scalars, segregated temp, segregated energy, all y+ etc Help me out with this Regards RD egr case1.JPG

February 26, 2013, 06:32		#2
siara817 Senior Member siamak rahimi ardkapan Join Date: Jul 2010 Location: Copenhagen, Denmark Posts: 220 Rep Power: 17	Have you tried to use pressure outlet for both inlet and outlet? __________________ Good luck Siamak

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February 26, 2013, 06:45		#3
rajeev50588 New Member Join Date: Feb 2013 Posts: 10 Rep Power: 13	yes i have done that too...i have mentioned the specified pressure given in the attachmnt for EGR inlet also along with this i have tried the target mass flow rate but of no use...m not getting the results as such

February 14, 2014, 13:20		#4
2pashtet New Member paul Join Date: Dec 2011 Posts: 5 Rep Power: 14	Hi, I have the same problem, I need to set pressure + masss flow inlet and pressure outlet. I try: 1) Inlet - Stagnation pressure (16 atm) Outlet - mass flow rate I get solution, where i have the same total pressure on the whole computational domain, it's wrong result 2) Inltet - Pressure outlet (16 atm) Outlet - Pressure outlet (0 atm) with target mass flow rate I get solution with wrong mass flow rate Help me please with advise Regards Paul

February 14, 2014, 16:03		#5
me3840 Senior Member Join Date: Nov 2010 Location: USA Posts: 1,232 Rep Power: 24	IMO the target mass flow option is not very good in STAR-CCM+, you can get better results by coding in the BC using Newton's method in Java.