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September 15, 2005, 04:43 
Halleluja!
Another one saved

#1 
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Niklas Nordin
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Halleluja!
Another one saved by the dimensionality check As you can see from your error message you have incompatible dimensions. fvm::ddt(scal) has 1/s, which means that all the other terms must have the same dimension. However, your svterm has (1/m)*(m^2/s)^(.5) = s^0.5, so you should check your terms, they are obviously incompatible, or there is a dimension in w1. N 

September 15, 2005, 04:47 
Dimension checking  does exac

#2 
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Gavin Tabor
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Dimension checking  does exactly what it says on the tin!
If your scal is dimensionless then when you take a time derivative you get something with dimensions [0 0 1 0 0 0 0]. On the rhs you took a square root. This is either wrong, or you need a prefactor to this term with the dimensions [0 0 0.5 0 0 0 0] to be physically correct. Gavin 

September 15, 2005, 06:04 
Hi guys,
Got that, and indee

#3 
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Radu Mustata
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Hi guys,
Got that, and indeed the w1 should have dimension of s^0.5. Then how do I define w1 with the right dimension? Thanks, Radu 

September 15, 2005, 06:17 
something like this...
dime

#4 
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Niklas Nordin
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something like this...
dimensionedVector w1 ( "w1", dimensionSet(0,0,0.5,0,0), vector(1,1,1) ); 

September 15, 2005, 06:25 
I've been trying to see how to

#5 
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Gavin Tabor
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I've been trying to see how to do this implicitly. The easiest way would be to do this:
solve ( fvm::ddt(scal) + fvm::div(phi,scal)  fvm::laplacian(sgsModel>nuEff(),scal) == fvm::Sp(sv1/scal,scal) ); A more elegant way would be to expand your term to get at least one involving (thing)*scal, and discretise that implicitly. Gavin 

September 15, 2005, 06:27 
Thanks Niklas,
So far so goo

#6 
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Radu Mustata
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Thanks Niklas,
So far so good. Seems to work fine now. Of course this is just a small part of what I want to do. Will get back later, hopefuly with no so easy questions. Radu 

September 15, 2005, 06:31 
Or use that... hope my mathsk

#7 
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Niklas Nordin
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Or use that... hope my mathskills are all forgotten.
grad(a) dot V = div(aV)  a *div(V) and since V is constant... div(aV) = grad(a) dot V hence, fvc::grad(...) = div(...,scal) Henry or Hrv will correct me if im wrong N 

September 15, 2005, 07:13 
Actually, V is not constant, s

#8 
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Niklas Nordin
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Actually, V is not constant, since nuEff is in there, V=nuEff*w1, so you cant drop that term.
It'll be something like fvc::grad(...) & w1 = fvm::div(..., scal) fvm::Sp(div(V), scal) Anyway, im leaving the details to you. You do the math. (hehe, I love to say that) N 

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