SIMPLEC coefficients modification?

AliE · February 9, 2019, 17:41

Hello cfd friends,

I am try to extend my solver based on SIMPLE to SIMPLEC. I have red something but it is not very clear to me what should I do. I am looking at the pressure matrix coefficients from openFoam but it does not help very much since I am missing some formulas here. Surely using an under-relaxation factor for the velocity equal to 1 some division by zero happens... Some of you guys has some hints for me?

As always Filippo, Paolo and LuckyTran you are very welcome to the discussion

Edit: I have prepared a simple 2D, 3x3 cartesian case with all the momentum coeffs and cell area known. So if you want we can discuss the case more in details

FMDenaro · February 10, 2019, 06:49

Could you better detail the case of the division by zero? Are we talking about the pressure matrix?

AliE · February 10, 2019, 06:55

Hi Filippo, I have solved the problem 5min ago! Yes I was stuck in understanding the pressure matrix, but now it is clear! After lunch I will write here the solution such that other people can understand how to do. Actually ot is not difficult at all improve SIMPLE to SIMPLEC.

To answer your question, in SIMPLEC the urf for velocity cannot be 1, because at some point you have to do 1/(aP/urf-sum(anb)) and this is 1/0 if urf=1.

ztdep · February 13, 2019, 07:37

Quote:

Originally Posted by AliE

Hi Filippo, I have solved the problem 5min ago! Yes I was stuck in understanding the pressure matrix, but now it is clear! After lunch I will write here the solution such that other people can understand how to do. Actually ot is not difficult at all improve SIMPLE to SIMPLEC.

To answer your question, in SIMPLEC the urf for velocity cannot be 1, because at some point you have to do 1/(aP/urf-sum(anb)) and this is 1/0 if urf=1.

Hello, the rule of thumb is to use the ap after relaxation. i.e. ap/relax.

February 9, 2019, 17:41	SIMPLEC coefficients modification?	#1
AliE Senior Member Join Date: Dec 2017 Posts: 153 Rep Power: 8	Hello cfd friends, I am try to extend my solver based on SIMPLE to SIMPLEC. I have red something but it is not very clear to me what should I do. I am looking at the pressure matrix coefficients from openFoam but it does not help very much since I am missing some formulas here. Surely using an under-relaxation factor for the velocity equal to 1 some division by zero happens... Some of you guys has some hints for me? As always Filippo, Paolo and LuckyTran you are very welcome to the discussion Edit: I have prepared a simple 2D, 3x3 cartesian case with all the momentum coeffs and cell area known. So if you want we can discuss the case more in details

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February 10, 2019, 06:49		#2
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,849 Rep Power: 73	Could you better detail the case of the division by zero? Are we talking about the pressure matrix?

February 10, 2019, 06:55		#3
AliE Senior Member Join Date: Dec 2017 Posts: 153 Rep Power: 8	Hi Filippo, I have solved the problem 5min ago! Yes I was stuck in understanding the pressure matrix, but now it is clear! After lunch I will write here the solution such that other people can understand how to do. Actually ot is not difficult at all improve SIMPLE to SIMPLEC. To answer your question, in SIMPLEC the urf for velocity cannot be 1, because at some point you have to do 1/(aP/urf-sum(anb)) and this is 1/0 if urf=1.