[Lee 小亢]

Hi everyone,
I met a problem in my work. I worked about the oxygen mass transfer between liquid and gas and I completed the process by using UDF. I defined a scalar in liquid and defined the oxygen as source term(transfer from gas to liquid). The problem is that if I don't define the diffusivity by UDF(ie, diffusivity is 1kg/m·s by default), it can computed but the result is not vary well, and I think the deviation is caused by the diffusivity. However, I changed the diffusivity to other constant for exampl 0.5, the computation diverged. And I also define the diffusivity by UDF and the computation diverged either. it noted that:"error：/（divide）：invalid argument [1]：erong type [ not a number]"
Can anyone who can give me some advice or tell me why I change the diffusivity,the computation diverged?

best wish~

[Lee 小亢]

Is there anybody can help me?

Thanks~