Learning Forum

[Shuan-Tai Yeh]

Hello everyone,

I'm relatively new to Autodyn and currently tackling a project involving the modeling of two-phase flow, specifically focusing on shape charge explosions. While I've found documentation regarding the properties of the solid phase, I'm now seeking clarity on how Autodyn calculates properties for the gas phase and the equations it employs for problem-solving. If anyone could point me towards relevant documentation or provide insights on this matter, I would greatly appreciate it. Thank you in advance.

[Chris Quan]

In Autodyn Component system in Workbench or Autodyn Standalone, if you create a new material, you will find the following Equation of State from the list: Tillotson, Puff, and Two-Phase.

Both Tillotson & Puff EOS are based on Mie-Gruneisen EOS. They can simulate the material phase change or vaporization during high velocity impact events. The gas phase is assumed to be an ideal gas behavior. Autodyn material library has the material data of Tillotson EOS and Puff EOS for some solid materials. Since these material data were generated from experiments under very specific conditions, please be cautious when using these material data. Verify the results carefully before applying them to your production models.

Two-Phase EOS can be used for fluids to model the phase change from liquid region to vapour region when pressure and temperature have changed. Saturation curve is used to separate the liquid & vapour regions. The saturation curve for water is provided with Autodyn.

 

[Shuan-Tai Yeh]

Hi Chris,

Thank you for providing such valuable insights. Your explanation regarding those EOS in Autodyn is greatly appreciated. I do have a follow-up question regarding simulating air (background) during events. While I understand Autodyn offers an ideal gas EOS for air, I'm curious about whether the governing equations (moment, energy) still rely on stress and strain. This aspect is a bit confusing me, especially in relation to obtaining gas properties from solid properties.