simpleFoam or pisoFoam, which is better?

Jingxue Wang · October 15, 2017, 10:42

Dear all

I am simulating the wind pressures on buildings using LES. I read from papers that PISO method converges with faster speed for transient problem than SIMPLE or SIMPLEC. So I adpoted pisoFoam to solve at first. But unluckily, it can only continue for several time steps and then the Corount number become very large and then the calculation stoped.I used simpleFoam to re-solve it again using the same mesh and the calculation can continue.

Do somebody has this experience before?Which method is much better with regards to simpleFoam and pisFoam?

Welcome any opinions!

Thanks!

Jingxue Wang · October 15, 2017, 22:01

Dear all

I find the similar thread pimpleFoam vs simpleFoam vs pisoFoam vs icoFoam?.

I find that the simpleFoam is a steady sovler in that thread,that means that it can not used for transient problem? In my case, the LES calculculation can proceed using simpleFoam but can not succeed using pisoFoam. I am really curious for this.

Do somebody have some idea?

[QUOTE=Jingxue Wang;667945]Dear all

piu58 · October 16, 2017, 01:25

If you do LES you cannot use simpleFoam. LES simulates the energy transfer form large to medium large eddies (and uses a model for energy transfer to even smaller ediies). This is a transient process and you need a transient solver for this. Simple is a steady stat solver.

I recommend pimpleFoam.

Jingxue Wang · October 16, 2017, 02:06

Quote:

Originally Posted by piu58

If you do LES you cannot use simpleFoam. LES simulates the energy transfer form large to medium large eddies (and uses a model for energy transfer to even smaller ediies). This is a transient process and you need a transient solver for this. Simple is a steady stat solver.

I recommend pimpleFoam.

Hi, Pilz

Many thanks for your reply!

I am still a little curious about simpleFoam.I checked some CFD books and found that SIMPEL method can also deal with trainsient problem.And also in fluent, the SIMPLE and SIMPLEC are also supported for LES. But in OpenFoam, the simpleFoam can not be used for transient problem?

Alasir · October 17, 2017, 18:45

I would also note that a spike in the courount number is characteristic of your simulation diverging.

October 15, 2017, 10:42	simpleFoam or pisoFoam, which is better?	#1
Jingxue Wang Member Jingxue Wang Join Date: Sep 2017 Posts: 58 Rep Power: 9	Dear all I am simulating the wind pressures on buildings using LES. I read from papers that PISO method converges with faster speed for transient problem than SIMPLE or SIMPLEC. So I adpoted pisoFoam to solve at first. But unluckily, it can only continue for several time steps and then the Corount number become very large and then the calculation stoped.I used simpleFoam to re-solve it again using the same mesh and the calculation can continue. Do somebody has this experience before?Which method is much better with regards to simpleFoam and pisFoam? Welcome any opinions! Thanks!

October 16, 2017, 01:25		#3
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	If you do LES you cannot use simpleFoam. LES simulates the energy transfer form large to medium large eddies (and uses a model for energy transfer to even smaller ediies). This is a transient process and you need a transient solver for this. Simple is a steady stat solver. I recommend pimpleFoam. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

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October 15, 2017, 22:01		#2
Jingxue Wang Member Jingxue Wang Join Date: Sep 2017 Posts: 58 Rep Power: 9	Dear all I find the similar thread pimpleFoam vs simpleFoam vs pisoFoam vs icoFoam?. I find that the simpleFoam is a steady sovler in that thread,that means that it can not used for transient problem? In my case, the LES calculculation can proceed using simpleFoam but can not succeed using pisoFoam. I am really curious for this. Do somebody have some idea? [QUOTE=Jingxue Wang;667945]Dear all

October 17, 2017, 18:45		#5
Alasir Member Anders Utnes Join Date: May 2017 Location: Norway Posts: 34 Rep Power: 9	I would also note that a spike in the courount number is characteristic of your simulation diverging.