use equations
 

Hi everyone!
I must use an equation in CFX to set a condition about the voltage.
The idea is to create something like this:
if the temperature is lower than 90° use a voltage of 60 V. If not decrease the voltage until the temperature is not lower than 90°.
do you know exactly which is the meaning of the following equation?
step((maxVal(Temperature)@REGION:B64-90 [K] )/1[K])*60[V]
how much is the value? 60 V if? :confused:
please, help me!!!!
thanks,
Ema

i've also tried to implement the following expression:
volt= 60[V]*(1/(1+e^(5*(maxVal(Temperature)@REGION:B97-90[K])/1[K]))) but my update failed...

your equation doesnt make any sence

step function returns 0 or 1 and your conditions should be non dimensional (thats why you divide the temperature by 1/[K] )

if you multiply by 60[V] then your expression has value either 0*60[V] or 1*60[V]

if you want to to create some feedback control search in the cfx manual for "Example: Feedback to Control Inlet Temperature"

You don't need to define the unit [K] after your maxVal(Temperature)@.... statement, as the value returned already has unit.

the units are for the 90[K]. the step function can look something like:
step( (T - 90 [K]) / 1[K] ) or
step( (T/1[K] - 90 )

exactly. Otherwise CFX will say you that the values are not correct.
What about my equation? why no sense at all? i was thinking to implement like a sigm function to multiply with the voltage...

True, disregard my previous post...

well you said you wanted to do some feedback. I replied that if you want to to create some feedback control search in the cfx manual for "Example: Feedback to Control Inlet Temperature". your equations as it stands dont do that :)