Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
How to use the result of each time-step as input to next time-step?
Posted May 20, 2019, 4:06 p.m. EDT General, Heat Transfer & Phase Change, Equation-Based Modeling Version 5.4 1 Reply
Please login with a confirmed email address before reporting spam
Basically this is how I would do it in hand calculation:
T_out_0 = 22 [degC] %% Guessed initial value.
%% at t=1:
COP(1) = 5[1/K] * T_out_0
T_out(1) = T_avg_Domain(1) - COP(1)/7[1/K]
%% at t=2:
COP(2) = 5[1/K] * T_out(1)
T_out(2) = T_avg_Domain(2) - COP(2)/7[1/K]
and so on ..
My problem is how to calculate COP from the previous T_out? When I define this in Variables node (As shown below), I got this warning: "circular variable dependencies".
COP : 5[1/K] * T_out
T_out : T_avg_Domain - COP/7[1/K]
Please login with a confirmed email address before reporting spam
Hi, you have to define an aditional variable Tav_old (add physics -> Global ODEs and DAEs). Add the equation 0=Tav_old-T_avg_Domain (variable: Tav_old, equation: Tav_old-T_avg_Domain. Then you add a "Previous Solution" subnode below the time dependent solver and solve for Tav_old. By this way you get Tav_old of the old solution.
Best regards Michael Rembe
-------------------Michael Rembe
Rembe Consulting PartG mbB
www.rembe-consulting.de