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radioss calculating time steps for high speed impact

meng2019

i need to do the simulation in radioss with very high speed impact, the simulating overall time is 500ns, and elements size is also 0.01um, how much of the time step? i run my model with these so small values, but it doen't work because i give the overall time step is too small. how i do in this case??

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Andy_20955

Radioss will automatically calculate a stable time step so you don't need to enter any time step. You can change the time step scale factor if you want Radioss to use a lower time step than what it has calculated. By default Radioss uses a time step that is 0.9*maximum stable time step. Some problems require using a lower time step scale factor like 0.67 but you can use the default of 0.9 and see how it works.

/DT

0.9 0

Thanks,

Andy

meng2019

Radioss will automatically calculate a stable time step so you don't need to enter any time step. You can change the time step scale factor if you want Radioss to use a lower time step than what it has calculated. By default Radioss uses a time step that is 0.9*maximum stable time step. Some problems require using a lower time step scale factor like 0.67 but you can use the default of 0.9 and see how it works.

/DT

0.9 0

Thanks,

Andy

thank you very much about your reply. i checked the.out file, i found the element and nodal time steps are all about e-8, there is no error about model, but when i started run the simulation, in the first step it stops the running, and having this message...what do you think about it in these photos?

im beginner in radioss, really need some helps, thanks very much!!

<?xml version="1.0" encoding="UTF-8"?>

Andy_20955

Hi,

Is your engine file named micro1_0001.rad?

What platform are you using Linux or Windows?

If you want to use a GUI to start the job then you can use the HyperWork solver Run manager which can be started in Windows by picking the Radioss menu.

On Linux you can use,

<install dire>/altair/scripts/radioss -gui.

For command prompt use,
Linux
<install_dir>/altair/scripts/radioss
Windows
<install_dir>/hwsolvers/scripts/radioss.bat

If running on one machine to run the job it should be,

<install_dir>/altair/scripts/radioss -np 8 micro1_0000.rad

where -np # is the number of cores you want to use.

Thanks,

Andy

meng2019

Hi,

Is your engine file named micro1_0001.rad?

What platform are you using Linux or Windows?

If you want to use a GUI to start the job then you can use the HyperWork solver Run manager which can be started in Windows by picking the Radioss menu.

On Linux you can use,

<install dire>/altair/scripts/radioss -gui.

For command prompt use,
Linux
    <install_dir>/altair/scripts/radioss
Windows
    <install_dir>/hwsolvers/scripts/radioss.bat

If running on one machine to run the job it should be,

    <install_dir>/altair/scripts/radioss -np 8 micro1_0000.rad

where -np # is the number of cores you want to use.

Thanks,

Andy

hello,

firstly thank you very much your help.

i have two files micro1_0000.dat and micro1_0001.dat. firstly i compiled the model in micro1_0000.dat in liunx (you can see the command in capture1), there is no error.

after i run it according to micro1_0001.dat (the running command in capture2), it gives me message, '** ERROR : INPUT FILE microl_0001.rad NOT FOUND', and '' ERROR TERMINATION
Attempting to use an MPI routine before initializing MPI', as i show you in the pictures last time.

thank you very much!

this problem is very important for me, thanks again!

shuangshuang

'

<?xml version="1.0" encoding="UTF-8"?>

Andy_20955

Hi,

The problems is you have named your files with the *.dat extension but your script is looking for files with *.rad extension. It is typical to use *.rad for Radioss files so I would recommend you change the extension of your files to *.rad.

I would also recommend you use a newer version of Radioss than 13 as this is very old.

meng2019

Hi,

The problems is you have named your files with the *.dat extension but your script is looking for files with *.rad extension. It is typical to use *.rad for Radioss files so I would recommend you change the extension of your files to *.rad.

I would also recommend you use a newer version of Radioss than 13 as this is very old.

im sorry, my files named is *.rad, i wrote it wrongly.

so what do think the probelm? it seems raleted MPI? i just checked a problem in forum, which is the same with mine, some said it is the MPI issue. you can see it from here

https://community.altair.com/community?id=community_question&sys_id=6d468c761b2bd0908017dc61ec4bcb8e

thanks again!

Andy_20955

I would suggest you try running without the MPI to make sure your model runs. Use the scripts that are included with HyperWorks and run without MPI by using -nt option.

<install_dir>/altair/scripts/radioss -nt 8 micro1_0000.rad

If this starts to run then you can try using the same script to run using the MPI. Are you running on one node or multiple nodes?

For one node,

<install_dir>/altair/scripts/radioss -np 8 -mpipath <path to mpirun> micro1_0000.rad

Is there a reason why you are using Radioss 13? That is very old. Can you upgrade to a newer version?

meng2019

I would suggest you try running without the MPI to make sure your model runs. Use the scripts that are included with HyperWorks and run without MPI by using -nt option.

<install_dir>/altair/scripts/radioss -nt 8 micro1_0000.rad

If this starts to run then you can try using the same script to run using the MPI. Are you running on one node or multiple nodes?

For one node,

<install_dir>/altair/scripts/radioss -np 8 -mpipath <path to mpirun> micro1_0000.rad

Is there a reason why you are using Radioss 13? That is very old. Can you upgrade to a newer version?

ok i try it as you suggested, after i will update for you the result.

thank you very much