[FLASH-USERS] 2D Spherical and Cartesian Geometry

[Carlo Graziani]

On 09/23/2016 09:16 AM, Michiel Bustraan wrote:
> Secondly, I did read the section in the userguide on geometries, and I understand that different geometries handle block volumes differently.
> But even so, shouldn't it be possible to simulate a 2D slice of a spherical shock using Cartesian geometry (say, a 2D simulation of the equator)?
> Or does the nature of the Cartesian geometry make it fundamentally inappropriate for this kind of simulation?
>

The nature of the Cartesian geometry make it fundamentally inappropriate 
for this kind of simulation.

2-d simulations assume a symmetry, and assign the "direction" of the 
symmetry along the y axis.  There are two available symmetries:  planar 
symmetry (d/dy=0) and azimuthal symmetry (d/dphi=0).  In the first case, 
the y axis represents invariant translation, in the second the y axis 
represents invariant rotation about the z-axis.

You select the first case by specifying "Cartesian", the second by 
specifying "Spherical".  The geometry selection selects symmetry, as 
well as block structure.

So, you see, as Mordecai noted, you can only produce an exploding line 
charge in cartesian geometry.  If you want a spherically-symmetric point 
explosion in 2d, your only option is spherical.

Carlo

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Carlo Graziani                                 (773) 702-7973 (Voice)
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