[aspect-devel] Help needed with setting up an EBA benchmark

[Wolfgang Bangerth]

On 09/04/2014 07:09 PM, Katrina Arredondo wrote:
> But why does it need to be nondimensionalized? Just to be consistent
> with the benchmark?

It doesn't have to be. The benchmark is defined in terms of 
nondimensional quantities -- it is what it is. But ASPECT does not take 
Rayleigh and Dissipation numbers as inputs. I have to somehow translate 
them into the physical quantities.


 > I guess I was thinking that this could be a test for how "easy" it is
 > to translate the geodynamics nondimensional terms into dimensional
 > terms in ASPECT. Otherwise why have the dimensional terms at all, if
 > it's too hard.

Because the real world is sufficiently complicated that 
nondimensionalization does not work. (For example, what exactly is the 
Rayleigh number when you have variable gravity, a geometry for which 
there is no obvious lengthscale, and thermal expansion and viscosity 
depend strongly on the temperature?) I think the better question is why 
we should have the nondimensional form if it only describes idealized 
but non-realistic situations :-)

Best
  Wolfgang

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Wolfgang Bangerth               email:            bangerth at math.tamu.edu
                                 www: http://www.math.tamu.edu/~bangerth/