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Old   June 29, 2009, 13:49
Default CEL expression
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jai
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below is my expression:
0.5 [kg s^-1]*step (1-t/1[s])*step (t/1[s]-2)

from 0 to 1 sec mass flow rate is 0.5kg/s and then 1-2sec mass flow rate is 0kg/s and then it is 0.5kg/s

i want to create expression for this condition:
0-1 sec = 0.5kg/s
1-2 sec = 0kg/s
2-3sec = 0.5kg/s
and so on....
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Old   June 29, 2009, 19:13
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0.5 [kg s^-1]*step (sin(pi*t/1 [s]))

I haven't used CFX12, so don't know if it's also possible to define this with the 'conditional functions' in CEL.


By the way, with your above expression, the flow is always zero
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Old   June 30, 2009, 10:36
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Quote:
Originally Posted by jai View Post
below is my expression:
0.5 [kg s^-1]*step (1-t/1[s])*step (t/1[s]-2)

from 0 to 1 sec mass flow rate is 0.5kg/s and then 1-2sec mass flow rate is 0kg/s and then it is 0.5kg/s

i want to create expression for this condition:
0-1 sec = 0.5kg/s
1-2 sec = 0kg/s
2-3sec = 0.5kg/s
and so on....
Try the following formula...

If x<a, then V1
If a<=x<b, V2
If b<=x<c, V3
If x>c, V4

Celfunction=V1*step(0.5-step( x/a ))+V2*step(step( x/a )-0.4)*step(0.5-step( x/b ))+V3*step(step( x/b )-0.4)*step(0.5-step( x/c ))+V4*step(step( x/c )-0.6)
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