[FLASH-USERS] [EXTERNAL] Re: Value of dt_hydro is going to negative infinity

[Prashant Tarey]

Hi Madhav,

It worked for me, I am using FLASH4.6, try this:

1) Setup the "FlatPlate" case with -3d flag, with the following command.
Here, instead of using a default name for object directory, I am naming the
object directory as "Flat3D", and any other name will also work
./setup FlatPlate -objdir=Flat3D -3d -auto

2)Copy the "flash.par.3d_naca_tested" file available in
"/source/Simulation/SimulationMain/FlatPlate/"; to the newly created object
directory "Flat3D", as "flash.par"
cp /source/Simulation/SimulationMain/FlatPlate/ flash.par.3d_naca_tested
Flat3D/flash.par

3) Compile the code,
make

4)The default case is "sim_number = 3 (naca2412);", and it is all set to run
mpirun -np 8 ./flash4
With just 8 processors, and "lrefine_max= 6", (the default value in
flash.par), the MAXBLOCKS limit exceeds, by setting "lrefine_max= 5", I was
able to run the simulation. If you have more processors, "lrefine_max     =
6" should work too.

Let me know how it goes!



Thank you.
Best regards,
Prashant Tarey
PhD Student, Mechanical Engineering
Duke 273
UNC Charlotte
NC, USA.





On Sun, Sep 26, 2021 at 11:33 PM Madhav Nagori <mnagori at uncc.edu> wrote:

> Hi Prashant,
>
> Thanks for your reply. Yes, I tried that. But the default cases are
> blowing up too.
>
> Best,
>
> Madhav
>
> On Sun, Sep 26, 2021 at 2:55 PM Prashant Tarey <tarey.prashant at gmail.com>
> wrote:
>
>> [*Caution*: Email from External Sender. Do not click or open links or
>> attachments unless you know this sender.]
>>
>> Hi Madhav,
>> Setup the case with -3d flag; in the object directory, replace the
>> flash.par file with the flash.par.3d file available in FlatPlate directory
>> and run the case. A default 3D airfoil case will run.
>>
>> On Sun, Sep 26, 2021 at 2:12 PM Madhav Nagori <mnagori at uncc.edu> wrote:
>>
>>> Hello Everyone,
>>>
>>> I am using the Flash 3D setup for my project. Before implementing the 3D
>>> setup to my specific problem, I am trying to run the default cases in
>>> FLASH. Once that is done, I will change the files to tailor it to my
>>> requirements.
>>>
>>> One of the 3D default cases in FLASH is of the cylinder. There is a
>>> simulation block in which a cylinder is placed and the flow over the
>>> cylinder is visualized. Since this is a default case, I didn't change any
>>> files which I downloaded from FLASH website and ran as it is.
>>>
>>> The simulation starts properly. But after a few time steps, the value of
>>> dt_hydro is going to a large negative value. As a result, the simulation
>>> blows up. Has anyone faced a similar problem? Any suggestions would be
>>> greatly appreciated.
>>>
>>> Thank you for the time.
>>>
>>> Best,
>>>
>>> Madhav
>>> --
>>> Best Regards,
>>>
>>> Madhav Nagori (he/him)
>>>
>>> PhD Candidate | Laboratory for Multiscale Computational Fluid Dynamics
>>> Department of Mechanical Engineering and Engineering Sciences
>>> University of North Carolina at Charlotte
>>> Office: Duke 273, 9330 Robert D. Snyder Rd, Charlotte, NC 28262, USA
>>> <https://www.google.com/maps/search/273,+9330+Robert+D.+Snyder+Rd,+Charlotte,+NC+28262,+USA?entry=gmail&source=g>
>>> Email: mnagori at uncc.edu
>>> LinkedIn: www.linkedin.com/in/madhav-nagori
>>>
>>
>
> --
> Best Regards,
>
> Madhav Nagori
>
> PhD Candidate | Laboratory for Multiscale Computational Fluid Dynamics
> Department of Mechanical Engineering and Engineering Sciences
> University of North Carolina at Charlotte
> Office: Duke 273, 9330 Robert D. Snyder Rd, Charlotte, NC 28262, USA
> Email: mnagori at uncc.edu
> LinkedIn: www.linkedin.com/in/madhav-nagori
>
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