wuweide127 发表于 2011-9-26 18:06:21

请问viscous pressure的具体公式是什么?

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 发表于 2011-9-28 05:11:55

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

wuweide127 发表于 2011-10-3 18:44:49

caoer 发表于 2011-9-28 05:11 static/image/common/back.gif
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 发表于 2011-10-4 04:43:15

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

wuweide127 发表于 2011-10-6 15:43:58

caoer 发表于 2011-10-4 04:43 static/image/common/back.gif
\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 发表于 2011-10-20 16:55:25

caoer 发表于 2011-10-4 04:43 static/image/common/back.gif
\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 massand velocity of each node, respectively. So what's the difference between the ls-dyna' damping and ABAQUS's viscous pressure?

caoer 发表于 2011-10-21 02:13:58

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

wuweide127 发表于 2011-10-24 15:03:43

caoer 发表于 2011-10-21 02:13 static/image/common/back.gif
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.
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