[IronLyon]

Hello, I have a question about the define of Piecewise function as inlet in CFX. Someone can help me?


The transisent process is 5 s in total, I would like to using two different fit linear to define the inlet, one from 0 to 1.5 s, the other from 1.5 s to 5 s.


The functions are show below:
func 1.PNGfunc 2.PNG


Both of the functions are quadratic function.


How can I achieve it in CFX?

[Opaque]

Say you have f1, and f2 to be switched at t = t_sw

F = step((t_sw - t) / 1 [s]) * f1 + (1 - step((t_sw - t) / 1 [s]) * f2

check it behaves correctly at t_sw

[IronLyon]

Originally Posted by Opaque

Say you have f1, and f2 to be switched at t = t_sw

F = step((t_sw - t) / 1 [s]) * f1 + (1 - step((t_sw - t) / 1 [s]) * f2

check it behaves correctly at t_sw

Thank you! I have checked, it did works! And it can be also written as

F = step((t_sw - t) / 1 [s]) * f1 + step((t - t_sw) / 1 [s]) * f2.


Before I thought ''step'' is only used to describe the step function, now has new idea how it works. Suppi!