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Old   July 8, 2008, 15:33
Default Orbital velocity Inlet expressions
  #1
rc2v07
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Hi

Im trying to simulate a wave in water on CFX, I have the following expressions for the X and Z velocity components:

U = w*a*Exp(k*z)*sin(wt-kz) W = w*a*Exp(k*z)*sin(wt-kz)

w = ang. freq.(rads/s) a = apm.(m) t = time(s) k = wave no.

Im not sure as to how to specify the x and z distances in CEL expressions, do I create a local co-ord frame in Pre at the inlet boundary? Also the time, do I use 't' or 'atstep' or neither.

The domain is a 2D rectangle with a foil at the centre, it is 3 (long) by 1.5 (wide) meters with openings at top and bottom and symmetry on front and back.

Currently my results with both t and atstep with and without creating a co-ord frame show almost parallel flow to the inlet and vertical flow thoughout the domain!

Thanks for the help!

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Old   July 11, 2008, 07:14
Default Re: Orbital velocity Inlet expressions
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MAB
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are you working in deep water scenario. Your equations for velocity components are wrong. it should be U= w*a*exp(k*z)*sin(w*t-k*x) and W=w*a*exp(k*z)*sin(w*t-k*x)

this expression is only true for deep water.
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Old   July 11, 2008, 07:45
Default Re: Orbital velocity Inlet expressions
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rc2v07
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yeah sorry mis-typed them the second z is x. but your eqtns are both the same the W components should be Cos. yeah Im doing deep water alright.
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Old   July 11, 2008, 08:51
Default Re: Orbital velocity Inlet expressions
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MAB
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yes it should be cos. just leave it as x , z and time as t , the velocities should work.
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Old   July 11, 2008, 10:43
Default Re: Orbital velocity Inlet expressions
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rc2v07
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yeah but where are x and z measured from?
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Old   July 11, 2008, 11:47
Default Re: Orbital velocity Inlet expressions
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MAB
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examine your geometry file in design modeller. you can note where the origin of these coordinate was. for example if you have created your wave tank with the left bottom corner at the origin (0,0,0) than thats where these coordinates are measured from. i hope it helps.

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Old   July 11, 2008, 14:21
Default Re: Orbital velocity Inlet expressions
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rc2v07
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yeah great thanks!
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