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Re: [lammps-users] Reg. AtC Fix_flux and computational domain problem
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Re: [lammps-users] Reg. AtC Fix_flux and computational domain problem

From: Steve Plimpton <sjplimp@...24...>
Date: Thu, 7 Dec 2017 07:33:03 -0700

The AtC folks will have to answer these Qs.


On Mon, Dec 4, 2017 at 1:57 PM, Parmar, Vinod <vparmar@...132...> wrote:

Dear Steve,

Thanks a lot for your valuable response. Experimentally It should not change by a significant number. When I tried to use "AtC source" instead of "AtC fix_flux" to deposit the input energy/fluence by femtosecond laser pulses, It did not have any effect on electron temperature (max). With "AtC source" command, electron temperature remained almost same if we increase the computational domain along x- and y-axis (when heat is influx along z-axis). 

That's why I was feeling, either there is some problem with "AtC fix_flux" command or the computed flux value what I have mentioned in the command (fix_modify AtC fix_flux electron temperature fcst 388860).

Does this computed flux value (388860) should increase as I increase the computational domain??

Kindly reply about this problem.

Thanking you in anticipation


Vinod Parmar
Fulbright Doctoral Research Fellow
School of Mechanical Engineering
585 Purdue Mall, Purdue University
West Lafayette, IN 47907

From: Steve Plimpton <sjplimp@...24...>
Sent: Monday, December 4, 2017 10:03 AM
To: Parmar, Vinod
Cc:; rjones@...3...; jeremy.templeton@...3...; sjplimp@...3...
Subject: Re: [lammps-users] Reg. AtC Fix_flux and computational domain problem
I suggest you do the expt.  Increase the flux by
the same ratio you are increasing the system size.
If the temp rise is the same, then you have your answer.


On Tue, Nov 28, 2017 at 11:21 AM, Parmar, Vinod <vparmar@...5511....> wrote:

Dear all,


I am using the user-atc package to simulate the fs laser ablation of nickel. I am struggling with an AtC problem since last three weeks. Actually I have used AtC fix_flux command to deposit about 0.3 J/cm^2 of fluence. I am getting an electron temperature (max) of about 20,000K (for computational domain of 0 10, 0 10, 0 100), that's fine. But as soon as I increase my computational domain (to 0 20, 0 20, 0 100) then my computed electron temperature (max) found to be only 2,000-3,000K only. My question is:

1. Am I suppose to change the flux value 388860 ((in the command fix_modify AtC fix_flux electron temperature fcst 388860 )when I increase the computational domain increases?

2. If not, then what else may be possible reason for the aforementioned problem?

I have taken advises from various active users, mailing lists and documentations but couldn't find any suitable solution. Thus finally asking to  to people behind the AtC programs. Kindly help me out.

Thanking you in anticipation

Vinod ​

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