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Old   May 14, 2018, 17:58
Question "if" expression problem
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Kim Gunhyeong
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Hey guys. I have problem in "if" expression.

I try to design butterfly valve model, so I make spherical shape domain which has vavle shape empty space in.

Then I give rotation speed to that domain, using expression;

if(ctstep<150[ ], 1.046[radian s^-1], 0)

but CFX error checker doesnt permit it. Whats problem? Plz help me
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Old   May 14, 2018, 18:18
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Glenn Horrocks
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Try:

if(ctstep<150, 1.046[radian s^-1], 0[radian s^-1])
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Old   May 15, 2018, 00:54
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urosgrivc
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ok, so the units are not ok,
but i think that the problem is in your simulation.
It might be the problem vith interfaces (sfere) have you split the surface or vhat does the conection look like

And you can plot your expresion, and use that, because it is great for troubleshoting it would give you an erorr if you would try to plot it before you run the solution.

Last edited by urosgrivc; May 15, 2018 at 03:31.
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Old   May 15, 2018, 09:55
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Kim Gunhyeong
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Quote:
Originally Posted by ghorrocks View Post
Try:

if(ctstep<150, 1.046[radian s^-1], 0[radian s^-1])

Thanks ghorrocks. I do as you recommend, so unit problem disappear

But CFX doesn't recognize "ctstep".(I find this expression at CFX post-processing - Current Time Step )

Is it wrong usage? Plz help me.
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Old   May 15, 2018, 12:32
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urosgrivc
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Use:
Acumulated time step it is in the wariables
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Old   May 15, 2018, 17:36
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Why not just use the real variable time "t" instead of time step?
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