请问viscous pressure的具体公式是什么？

wuweide127

第一次在这里发帖，诚惶诚恐，希望没有问的太低级。

在ABAQUS中可以运用viscous pressure帮助控制动能，但在ls-dyna中我还没有找到这个功能，所以想自己用公式加载。但是找遍了所有的help文件，也没有找到相应的公式。请问有人知道吗？谢谢！

caoer

should be sort of history-dependent pressure, the help document of soft should specify the parameters and related funciton.

wuweide127

caoer 发表于 2011-9-28 05:11
should be sort of history-dependent pressure, the help document of soft should specify the parameter ...

谢谢版主的回复！

我找到公式了，如附件所示。但是我对定义中的对n的解释“ the unit outward normal vector to the surface at the same point”不理解。是说n只是一个单位吗？还是有具体的数值，即垂直于表面的距离？

再次感谢！

caoer

\vec{n} is a normalized vector, represents the direction of velocity.
the dot product of two vectors is a scaler value. thats it.

wuweide127

caoer 发表于 2011-10-4 04:43
\vec{n} is a normalized vector, represents the direction of velocity.
the dot product of two vectors ...

Got it.
Thank you for your detailed explanation!

wuweide127

caoer 发表于 2011-10-4 04:43
\vec{n} is a normalized vector, represents the direction of velocity.
the dot product of two vectors ...

Hi Caoer,

In ls-dyna, I found damping settings and I am trying to use global damping. The explanation of global damping is a kind of force applied to each node, F=-f(t)mv, where f(t) is a curve representing damping fator, m and v should be the mass  and velocity of each node, respectively. So what's the difference between the ls-dyna' damping and ABAQUS's viscous pressure?

caoer

i think it is similar, difference may lie in the pressure and force.

wuweide127

caoer 发表于 2011-10-21 02:13
i think it is similar, difference may lie in the pressure and force.

thank you, caoer. I will have some tests and show the results later.