Hi Array and ArraynThank you for the comments. nYes I have checked the logic for the if statements. There are no gaps in temperature, and as Array pointed out even if there is gap it should execute the else statementnof Cp 850 J/kgK. It is strange for me. nI get a warning in all the iterations (total 500 iterations) and the warning is also at different temperatures. Since I was testing this UDF, my mesh is very coarse and hence very low residuals. I hope this is not an issue.Let me know nThanks,nAshishn