MULES in Eulerian solvers

MMNCH · July 2, 2020, 13:25

Dear all friends...

I have an ambiguity about Eulerian solvers.
It is completely reasonable to use MULES in VOF based solvers like interFoam to keep the interface sharp. but in the eulerian based solvers like twoPhaseEulerFoam, multiPhaseEulerFoam, reactingEulerFoam, etc., why this limiter is used?
If I'm not mistaken, eulerian based solvers are not able to capture the interface and the nature of these methods is associated with dispersion , so what is the purpose of using this limiter in these solvers?
Can anyone clarify this issue for me?

Thanks in advance...

gianniTre · July 7, 2020, 13:25

Hi,

The main goal of MULES is to keep the scalar bounded without limiting to an upwind scheme. So more than keep the interface sharp the results is to reduce the numerical diffusion (which is kind of the same thing but more as a side effect).

What is designed to keep the interface sharp is mainly the "compression" velocity. You control this compression through the constant Calpha.

All the solvers you mentioned use MULES primarily to ensure a bounded solution limiting the numerical diffusion.

Cheers,
Giovanni

MMNCH · July 7, 2020, 13:58

Dear Dr. Tretola

Thank you very much for your reply.

July 2, 2020, 13:25	MULES in Eulerian solvers	#1
MMNCH New Member mohammadmahdi noroozi Join Date: Oct 2017 Posts: 9 Rep Power: 8	Dear all friends... I have an ambiguity about Eulerian solvers. It is completely reasonable to use MULES in VOF based solvers like interFoam to keep the interface sharp. but in the eulerian based solvers like twoPhaseEulerFoam, multiPhaseEulerFoam, reactingEulerFoam, etc., why this limiter is used? If I'm not mistaken, eulerian based solvers are not able to capture the interface and the nature of these methods is associated with dispersion , so what is the purpose of using this limiter in these solvers? Can anyone clarify this issue for me? Thanks in advance...

July 7, 2020, 13:25		#2
gianniTre New Member Giovanni Tretola Join Date: May 2015 Posts: 4 Rep Power: 10	Hi, The main goal of MULES is to keep the scalar bounded without limiting to an upwind scheme. So more than keep the interface sharp the results is to reduce the numerical diffusion (which is kind of the same thing but more as a side effect). What is designed to keep the interface sharp is mainly the "compression" velocity. You control this compression through the constant Calpha. All the solvers you mentioned use MULES primarily to ensure a bounded solution limiting the numerical diffusion. Cheers, Giovanni MMNCH likes this.

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July 7, 2020, 13:58		#3
MMNCH New Member mohammadmahdi noroozi Join Date: Oct 2017 Posts: 9 Rep Power: 8	Dear Dr. Tretola Thank you very much for your reply.