I am using CFX11. Can anybody help me that how to find the additional variable %mass(kg) which leave the outlet at a specific time in a transient solution

Some functions can be obtained from the function calculator. Is the %mass mean mass fraction? If so, you can obtain the massflow of outlet for each component, and then calculate manually or using customer defined variable.

Thanks Rikio, My problem is that i run the simulation 1st for steady state and then use these results for transient rum. I selected monitor points at inlet and outlet to monitor the concentration of additional variable (kg m^-3. But when I output data from solver the conc. at monitor pt1(inlet) is 0.98 (kg m^-3) but at outlet the conc. is only 0.06(kg m^-3). Is something wrong with my setting?? How can I take the X percent(any percent) of additional variable at outlet. Please any body help

At first you should check your imbalances, i.e. whether (especially in your steady-state simulation) the amount of your additional variable coming in at inlet is also coming out; otherwise you still need more iterations.

Then, is concentration is in kg/m^3 it is a concentration density, and you can directly compare this with fluid density. Take the function calculator in CFX-Post and calculate areaAve of concentration at outlet divided by areaAve of density at outlet, then you have the ratio; multiply with 100, then you have percentage.

Thanks andreas, But there is still problem that i can not see in CFX post the function variable Concentration. Please have a detail look

The tracer at the inlet was added by the following eq. ExpFunction= fc*(1/(1+exp(-alpha*(t-sher ))))*(1-1/(1+exp(-alpha*(t-sher )))), alpha= 0.5[s^-1], fc = 1[kg m^-3], sher = 15[s], mass flow rate at inlet = 0.005kg s^-1, mass flow rate at outlet = 0.005kg s^-1, The solution was run for 20000s as transient and convergence level is 10^-6. but i can not get the percentage of mass flowing away the outlet. please help