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Old   May 12, 2008, 11:20
Default WAVES
  #1
MAB
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i am modelling waves in CFX 11.0 . My question is how to achieve non-reflecting boundary conditions at the other end of the free surface to avoide wave refelection. Any answere 'll be appreciated. thanking in advance.

MAB
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Old   May 12, 2008, 21:35
Default Re: WAVES
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HoJun
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I think that you will calculate the transmission loss in your model. but, the acoustic wave model is not suffient in CFX. In general, LMS.Virtual.lab or SYSNOISE is to be used.

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Old   May 13, 2008, 09:34
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Dr. V. Kumar
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I doubt that you can solve wave propagation problems with CFX without any additional programming (wave equation). CFX is for solving Navier-Stokes equations, i.e. problems involving fluid flow.

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Old   May 13, 2008, 13:44
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longbow
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Non-reflecting BC is a Beta feature of CFX-11.
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Old   May 13, 2008, 20:22
Default Re: WAVES
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HoJun
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Hi, In my opinion, It is good solution to handle acoustics loss problem by SYSNOISE. and, anechoic termination(non-reflective B.C.) also can be applied in easy. In general, The transmission loss or Insertion loss is defined in frequency domain. CFX output will be the time-domain data. So, It transformed for frequency analysis by Fourier transform. So, additional post-processing is to be done using commercial s/w. i.e. Mathworks MATLAB or MS-excel.

for now. I don't solve the transmission loss i.e. exhaust muffer in CFX. If you have a simple example. I will study by CFX.

Sincerely yours.

HoJun
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Old   May 15, 2008, 08:43
Default Re: WAVES
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Phil
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The nonreflective BCs available for acoustic waves are not appropriate for free surface waves. Instead, it is useful to 'absorb' the waves in a subdomain upstream of the outlet using a momentum source. Contact your tech support for details.
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Old   May 15, 2008, 09:54
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Andreas
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To avoid reflections, you can use a "numerical beach": Behind the area of interest (e.g. ship) your grid should be go fast coarser in wave direction, e.g.:||||| | | | | | With this little trick all waves will be disturbed before they reach your outlet and you can use a "stillwater" condition at the outlet. Andreas
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Old   May 15, 2008, 12:50
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MAB
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thanks Andreas , I think your suggestion is the easiest way to achieve the required condition.
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Old   August 19, 2009, 07:39
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  #9
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Hi, I am also modelling waves in CFX 11.0 . I have read this post about achieving non-reflecting boundary conditions at the end of the domain.

I have tried to avoid reflections using Andrea´s suggestion but as I have to refine the mesh horizontally to see clearly the crests (to define well the waves shape) I cannot refine the mesh vertically at the same time (at least with CFX Mesh)

Anyone could kindly give me advice about it?

Thank you
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Old   December 12, 2012, 16:00
Default Tutorials for wave generation
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niru
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Hi

Is there any tutorial for modelling waves.
I came across a numerical beach simulation. I would like to know if there are any tutorial files available for doing this.
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