Ok. I understand. I see the logic of saving on some operations.
> Argulably, these quantities should be calculated in some
> sort of ratio so the absolute value of the volume won't matter.
Unless you have a source with a defined integral absolute value. But I agree
that in general "theta = 1" is not a problem, as long as it's clear from the
documentation.
--
Pavel
> On 15 Jan 2020, at 17:34, Daniel Wheeler wrote:
>
> On Wed, Jan 15, 2020 at 4:21 AM Pavel Aleynikov
> wrote:
>>
>> Hi,
>>
>> How are "mesh.cellVolumes" defined in fp.CylindricalGrid1D case?
>> The surface of a circle grid is not equal pi*r^2.
>>
>> import fipy as fp
>> L= 1.; nx = 1000
>> mesh = fp.CylindricalGrid1D(dx=L/nx, nx=nx)
>> print(mesh.cellVolumes.sum())
0.5
>>
>> Why not pi?
>
> I'm not sure. It's an arbitrary choice though. The angle was chosen as
> "1" rather than "2 * pi". The volume of an element is "theta * r * dr"
> where "theta" is the
> angle, "r" are the cell centers and "dr" is the cell spacing. It's
> possible that by choosing "theta=1", then the "theta" can be omitted
> saving an extra operation.
>
>> How should I integrate Variables on such a grid?
>> (2*pi*Var*mesh.cellVolumes).sum()?
>
> Makes sense. Argulably, these quantities should be calculated in some
> sort of ratio so the absolute value of the volume won't matter.
>
> --
> Daniel Wheeler
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