Re: [arts-users] generating scattering data

2022-04-28 Thread Patrick Eriksson

Hi,

Adding to Oliver's answer. Failing convergence should mainly be an issue 
of size parameter. We have not investigated this in detail, but the 
limit for this code seems to be at size parameters of 5-10.


Bye,

Patrick


On 2022-04-27 22:33, Krolick, William C. (MSFC-ER42)[ESSCA] wrote:

Hello,

I have been attempting to generate some scattering data files with the 
command “scat_data_singleTmatrix(…”, and am running into some issues. I 
get the following error after running for a while: “CONVERGENCE IS NOT 
OBTAINED FOR NPN1=300. EXECUTION TERMINATED“. I am running with a 
wavelength range of 3.5e-7-6.8e-7 meters and between 50-500 grid points. 
Increasing the wavelength does make the code with the given run file 
converge, but I would of course like to have it converge for my desired 
range. Any obvious things to look at to debug this issue?


Thank you,

Will Krolick

Senior Project Engineer, CFD Analyst

NASA Marshall Space Flight Center, ER 42

Jacobs Space Exploration Group, ESSCA

CFD Research Corporation



Re: [arts-users] generating scattering data

2022-04-28 Thread Lemke, Oliver
Hi Will,

ARTS is using the Tmatrix code by the late M. I. Mishchenko. While generally 
working very well, it is known to have certain limitations depending on the 
chosen combination of parameters. We ran into similar issues before and 
sometimes could regain convergence by tweaking the aspect ratio. But I'm afraid 
I cannot give you a good hint on how to circumvent these issues. You might want 
to have a look at the Tmatrix publications that describe the method in detail 
listed in the documentation here:

https://github.com/atmtools/arts/blob/master/3rdparty/tmatrix/License.txt

Cheers,
Oliver


> On 27 Apr 2022, at 22:33, Krolick, William C. (MSFC-ER42)[ESSCA] 
>  wrote:
> 
> Hello,
>  
> I have been attempting to generate some scattering data files with the 
> command “scat_data_singleTmatrix(…”, and am running into some issues. I get 
> the following error after running for a while: “CONVERGENCE IS NOT OBTAINED 
> FOR NPN1=300.  EXECUTION TERMINATED“. I am running with a wavelength range of 
> 3.5e-7-6.8e-7 meters and between 50-500 grid points. Increasing the 
> wavelength does make the code with the given run file converge, but I would 
> of course like to have it converge for my desired range. Any obvious things 
> to look at to debug this issue?
>  
> Thank you,
> Will Krolick
>  
> Senior Project Engineer, CFD Analyst
> NASA Marshall Space Flight Center, ER 42
> Jacobs Space Exploration Group, ESSCA
> CFD Research Corporation



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