/EBCS/PRES condition for explosion simulation

Taylor_Wang

Hi,
i have a problem when i used the /ebcs for under water explosion simulation. the ebcs is applied on the none reflecting boundary. as my understanding, the boundary should keep the boundary pressure constant. but in reality it will change with time decay, how can i resolve such issue or any other pressure i can use?

or any other i can use to keep the boundary pressure constant?
the material law is law 51, NRF is the iform=6, and TNT and water two phases are included in the simulation
Thanks for anyone who can help

below is the pressure plot at boundary using /ebcs/pres keywords

 

Polyvios Romanidis

Hi Lei,

Based on your model description you have insert two modeling techniques that try to achieve the opposite thing. 

More precisely, the NRF material you have insert try to change the pressure in order to prevent pressure waves and reverse flow phenomena.  The exact type used for the calculation of the pressure can be found in the following link:

https://help.altair.com/hwsolvers/rad/topics/solvers/rad/boundaries_iform_6_starter_r.htm (Comment 1)

On the other hand the /EBCS/PRES was used aiming to keep the pressure constant.  So, the effect of both formulations can not be seen at the same time.

Generally, you can not have NRF and constant pressure at the same time!

Polyvios