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-   -   Problem in generating linear Wave !? (http://www.cfd-online.com/Forums/cfx/109899-problem-generating-linear-wave.html)

mystar November 29, 2012 03:05

Problem in generating linear Wave !?
 
Dear all,
I am trying to generate linear Wave in CFX,..
I all so make following conditions:
@Inlet : i applied velocity at Ui and Vi ; and Fluid Values: water= WaterI
@Outlet: Relative Pressuer is Hypers, Fluid value is Zero gradient
WaterI = if(y<WaterSurface, 1, 0)
Hypres= if(y >WaterSurface, 0[Pa], (997-1.185)*g*(WaterSurface-y))
WaterSurface = 0,5*H*Cos(2*pi*(x/L-t/T))
Ui = pi*H /T *cosh(2*pi*(y+d)/L )*cos(2*pi*(x/L -t/T))/cosh(2*pi*d/L )
Vi = pi*H /T *sinh(2*pi*(y+d )/L )*sin(2*pi*(x/L -t/T))/sinh(2*pi*d /L )

H: wave height
L: wave length
T wave period
d: mean water depth


But, my result is non-reasonable,... Pls ponit me what is wrong ?

thank and sorry for my English

ghorrocks November 29, 2012 16:20

If you want us to help you, you will have to describe what happened. What is not reasonable about it?

mystar November 29, 2012 20:33

2 Attachment(s)
Quote:

Originally Posted by ghorrocks (Post 394928)
If you want us to help you, you will have to describe what happened. What is not reasonable about it?

Frist of all, i am wondering my applied boundary conditions right or wrong for linear wave ?
Followings describes my problem, The result is nonreasonable and i dont understand it

pls let me know what is wrong here !

Many thank and Brg

PeMo November 30, 2012 10:20

First seems like you didnt initialise the model. For 2-Phase transient flow it is necessary to define the area of water before the simulation. I did this 2D numerical wave channel thing in Fluent a couple of years ago, so the main problem is not to generate the waves, it is to get the waves out of the model. Fluent supported this with sth called numerical beach treatment, maybe you have similar functions in CFX. No ideas if your formulas are right but you have to differentiate between shallow and deep water waves, which you will find with the right formulars in every good book about free surface/open channel flow

mystar December 3, 2012 22:13

2 Attachment(s)
Quote:

Originally Posted by PeMo (Post 395036)
First seems like you didnt initialise the model. For 2-Phase transient flow it is necessary to define the area of water before the simulation. I did this 2D numerical wave channel thing in Fluent a couple of years ago, so the main problem is not to generate the waves, it is to get the waves out of the model. Fluent supported this with sth called numerical beach treatment, maybe you have similar functions in CFX. No ideas if your formulas are right but you have to differentiate between shallow and deep water waves, which you will find with the right formulars in every good book about free surface/open channel flow

Dear Pemo and all, i also define the initialisation for each phase by Waterini expression... and i try to make another example by following attackment, file CFD-Online.ccl, but when i run it... the error "Floating point" is occured
Imagine define my model, CFD-Online.ccl define boundary condition i made... pls see and correct it

Thank so much !


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