5 fluent表达式报错name 'StaticPressure' is not defined ？

表达式内容：Name：DensityH2Definition：StaticPressure*0.002[kg/mol]/R/StaticTemperature想作为氢气密度参数，但编辑完成后console一直提示：Setup contains invalid expression.Expression Error UsedIn========== ===== ======DensityH2 name 'StaticPressure' is not defined hydrogen->densitySetup contains invalid expressions.这种情况是哪里出了问题？该怎么办？