iteration is not working for only argon

Gil

Hi~

I simulate about low pressure chamber. so I apply slip boundary condition in viscous panel.

when I select an air as material, iteration make progress.

but

when I select an argon, iteration don't make progress.

only "floating point error : invalid number" error message is presented.

I check properties of Ar, and also put in a thermal accomdation constant.

but..... I don't know a reason.

give me a help.... please...