利用PRO/II模拟管道压力降计算? 计算报错,如下: 1 error(s), 0 warning(s), and 0 message(s) detected: *** error *** unit 1, 'pi1' - liquid viscosity, vapor viscosity, and surface tension methods are required by the pipe unit. ensure that methods are declared for them in the thermodynamic method set assigned to this pipe unit.查看更多