dimensional or dimensionless?

amin66 · July 28, 2012, 17:29

Hi Foamers

can some1 clear this for me plz:
is OpenFoam a dimensional solver? or dimensionless solver like fluent?

nimasam · July 29, 2012, 09:45

fluent is dimensionless solver?
however OpenFOAM, check dimensions, and its dimensional solver without doubt

amin66 · July 29, 2012, 14:47

Thanks Nima
i think i couldn't ask my question in a good way!

my means was that if in simulation we want the Re=(u*d)/nu=180 , Can we set velocity(u), diameter(d) or nu in arbitary values to obtain Re=180 ?

means: is simulation with u=180 m/s , d=1 m , nu=1 same with simulation with u=180*10^-6 , d=1 , nu=10^-6 ????

Regards

niaz · July 29, 2012, 15:50

mathematically, yes. but by the view of numerical method, it maybe has differences for numerical methods used.
but I checked it for a single cylinder as a test case, I have got the same answers.
U=100, nu=1,<==>U=1,nu=0.01
but there is difficulty in convergence of answer in first test case.

amin66 · July 30, 2012, 08:37

Thanks niaz, was useful

So, i can change the values of air and water's properties in interfoam to obtain the Reynolds and Froude number that i want. and the only difficulty is convergence?

niaz · July 30, 2012, 14:27

Quote:

Originally Posted by amin66

Thanks niaz, was useful

So, i can change the values of air and water's properties in interfoam to obtain the Reynolds and Froude number that i want. and the only difficulty is convergence?

yes, but be careful, to change all parameters correctly manner.

amin66 · August 1, 2012, 09:20

Thank you so much

July 28, 2012, 17:29	dimensional or dimensionless?	#1
amin66 Member Amin Join Date: Mar 2012 Posts: 60 Rep Power: 14	Hi Foamers can some1 clear this for me plz: is OpenFoam a dimensional solver? or dimensionless solver like fluent?

July 29, 2012, 15:50		#4
niaz Senior Member A_R Join Date: Jun 2009 Posts: 122 Rep Power: 17	mathematically, yes. but by the view of numerical method, it maybe has differences for numerical methods used. but I checked it for a single cylinder as a test case, I have got the same answers. U=100, nu=1,<==>U=1,nu=0.01 but there is difficulty in convergence of answer in first test case. amin66 likes this.

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July 29, 2012, 09:45		#2
nimasam Senior Member Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,267 Blog Entries: 1 Rep Power: 25	fluent is dimensionless solver? however OpenFOAM, check dimensions, and its dimensional solver without doubt

July 29, 2012, 14:47		#3
amin66 Member Amin Join Date: Mar 2012 Posts: 60 Rep Power: 14	Thanks Nima i think i couldn't ask my question in a good way! my means was that if in simulation we want the Re=(ud)/nu=180 , Can we set velocity(u), diameter(d) or nu in arbitary values to obtain Re=180 ? means: is simulation with u=180 m/s , d=1 m , nu=1 same with simulation with u=18010^-6 , d=1 , nu=10^-6 ???? Regards

July 30, 2012, 08:37		#5
amin66 Member Amin Join Date: Mar 2012 Posts: 60 Rep Power: 14	Thanks niaz, was useful So, i can change the values of air and water's properties in interfoam to obtain the Reynolds and Froude number that i want. and the only difficulty is convergence?

August 1, 2012, 09:20		#7
amin66 Member Amin Join Date: Mar 2012 Posts: 60 Rep Power: 14	Thank you so much