So, I have successfully created the expression "mdot" and assigned it the units and value in its definition as 0.05[kg s^-1]. I have done this part "/define/periodic-conditions/massflow-rate-specification? 5 0. 0.5 2 300 1. 0. 0" correctly. I have also verified by using "define/named-expressions/compute mdot" and it returned the value 0.05 kg/s. "mdot" shows up in the workbench 'parameter set' window and I tried to change the value of mdot by adding more cases over there and simulate it. But the mass flow rate did not change for each case and it was the same thing that I put in the periodic dialog box for the first case. So this confirms that the parameter I have created wasn't accepted as the parameter for the massflow rate in the periodic condition. Can you tell me what I have done wrong? I have created a journal file too and tried to edit in that but it seems I have to read the journal file every time I have to change my mass flow rate or put in the TUI commands to change the mass flow rate. Either I am understanding it wrong or I am not using it the right way. Can you clarify?