程序老是提示出错，说是没定义体积变量，谁给解答一下啊，谢谢Error : NO BULK MODULUS IS DEFINED FOR ACOUSTIC ELEMENT 23 INSTANCE PART-1-1. ALL ACOUSTIC ELEMENTS MUST HAVE NONZERO BULK MODULUS DEFINED USING *MATERIAL AND *ACOUSTIC MEDIUM.
Error : NO BULK MODULUS IS DEFINED FOR ACOUSTIC ELEMENT 23 INSTANCE PART-1-1. ALL ACOUSTIC ELEMENTS MUST HAVE NONZERO BULK MODULUS DEFINED USING *MATERIAL AND *ACOUSTIC MEDIUM.
Error : INITIALIZATION OF ACOUSTIC ELEMENT MATERIAL POINT DATA FOR ELEMENT 23 HAS FAILED BECAUSE NO BULK MODULUS EXISTS FOR THISELEMENT.
