[FLASH-USERS] xflash3 and 3D spherical coordinates

[Massimo Gaspari]

I've tried many tests, changing min max coords, CFL number, NXB vs NYB/NZB. Initial conditions (rho, temp, etc.) seem ok (using visit), but in the first timestep I always receive, with gdb (and -fpe0 enabled), this error in avisco.F90:

 

Program received signal SIGFPE, Arithmetic exception.
avisco (j=5, k=5, avis=..., dirgeom=..., xyzswp=2, nzni=5, nznf=13, nsdim=3, xtop=8.364632500000001e+23, xbot=-2.3767975000000004e+23,
    ytop=4.4465908125712189e-323, ybot=4.4465908125712189e-323, ylft=4.4465908125712189e-323, yrgt=0, zlft=-0.19634954084936207, zrgt=0.58904862254808621,
    x=..., xl=..., xzn=..., yzn=..., zzn=..., u=..., uttp=..., utbt=..., utrt=..., utlt=..., cvisc=0.10000000000000001) at avisco.F90:417
417                   avis(i) = (sin(x(i)) * u(i) - sin(x(i-1)) * u(i-1)) /        &


I've print:

(gdb) print dytb
$2 = 7.9050503334599447e-323
(gdb) print dxtb
$3 = 2.5055296642745135e-72
(gdb) print dztb
$4 = 6.9533558064452965e-310

 

I think around the polar region, coords differences (dytb, etc..) may go to zero (and so denom), but I still don't know how to avoid or fix this. As I said I tried changing min rad (and also max theta to 180 and phi to 360), but this error continues to appear with low or high refinement (40 blocks or 1000 blocks). 

Hints?


 
> Date: Thu, 25 Mar 2010 14:41:26 -0500
> From: klaus at flash.uchicago.edu
> To: gaspmax at hotmail.com
> CC: flash-users at flash.uchicago.edu
> Subject: Re: [FLASH-USERS] xflash3 and 3D spherical coordinates
> 
> On Thu, 25 Mar 2010, Massimo Gaspari wrote:
> 
> > 
> > Hi all,
> > I'm trying to plot with xflash3 a chk output created by 
> > a simulation in spherical coordinates (r, theta, phi). Does it work?
> > (User's guide says that it is supported)
> 
> Sorry, I've never tried this.
> 
> It should be possible to trick xflash3 into ignoring the geometry
> and treat the data as Cartesian (by making some simple change in
> xflash3.pro), so you get at least *some* visualization with xflash3.
> But again, I have never tried this for 3D spherical.
> 
> 
> > Another question: have you tested 3D spherical coordinates with any hydro problem?
> > Should I avoid them? 
> 
> Hydro with 3D spherical coordinates "should" work. However, we have not 
> tested it ourselves and are not using it. We would welcome any reports on
> your experiences.
> 
> I say it "should" work because 3D Cartesian as well as 1D and 2D spherical
> are know to work, and the 3D spherical case does not add any essentially
> new complications to the code.
> 
> That was an answer from the code perspective. If it makes physical sense 
> to use spherical coordinates is another question. Also whether the 
> behavior at the poles and especially at the origin are represented well 
> enough in those coordinates (without excessive refinement) is open (and 
> should depend on your problem). 3D Cartesian may be preferable for such 
> reasons.
> 
> Klaus
 		 	   		  
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