Learning Forum

[hweimeng]

Wonder whether people encounter the problem where no matter how high the minimum density factor is set (under material cutoff), the mass of the material in the Euler cell will not be constrained. I did a test case of air escaping from Euler elements and set my minimum density factor to 1000. The final mass in the Euler cell is still lower than the calculated threshold..  

[Chris Quan]

The Minimum Density Factor is used to limit the transport of extremely small amount of mass. It is not used to limit the amount of mass in an Euler element in Autodyn. 

The default value of the Minimum Density Factor is 1E-4. Thus if the amount of mass being transported from one element to another element is less than the Minimum Density Factor x Reference Density of a material, Autodyn will not transport this amount of mass. It will transport the mass in next cycle or cycles (time step) when the mass being transported exceeds the Minimum Density Factor x Reference Density.

The proper use of Minimum Density Factor can help to prevent the error and warning messages such as energy balance error and time step too small.