hot oil flows through centre with cold surrounding water flowing in opposite direction. I have already calculated the theoretical length using data in the table & formulas. I then used this length value for the ansys fluent geometry. i need to now validate the trueness of this length value using cfd results, making sure the engine oil temperature has decreased from 350k to 310k. i have just finished the solution stage but currently not sure what to plot to validate the trueness of this theoretical calculated length?