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-   -   InterDyMFoam SDA SKA coefficients (http://www.cfd-online.com/Forums/openfoam-solving/58188-interdymfoam-sda-ska-coefficients.html)

 markc December 18, 2008 10:56

Hello, I am studying the OF

Hello,

I am studying the OF 1.5 interDyMFoam tutorials.
In the dynamicMeshDict the motion of the body is described by "solidBodyMotionFunction SDA;"
I found that SDA stands for Ship Design Analysis and SKA for Sea Keeping Analysis.
However, I have some questions regarding the various coefficients.
As the tutorials intend to calculate the sloshing motion of a liquid in a tank, it is clear that you have to describe the motion of the solidBody (tank in this case). One important parameter is Tpn (natural period of the ship). But there is also a coefficient called "Tp", natural period of liquid. This surprises me because this sounds like you have to know the natural period of the sloshing liquid. In my understanding this is not an input but an output: one wants to calculate a natural period of a tank-liquid system.
Some other parameters I have questions about:
- There is min and max roll amplitude. Does this mean that the amplitudes of the solid body are varied between these 2 values?
- What exactly happens with the model scale ratio lambda?
- What is the purpose of dTp and dTi?

Hope that someone can shed a light as this solver and bodymotion class seems very interesting for a lot of applications.

Mark

 lostin4ever October 23, 2009 15:37

Controlling motion of tank in tanksloshing problem

I am trying to simulate tank sloshing problem in openfoam using interdyfoam solver and I am puzzled about the dynamicmeshdict file. I am not able to figure it out how we are giving the tank motion input? In my case I just need to do some horizontal displacement with a particular constant frequency (no rolling). Can you guide main in this regards?

 lostin4ever October 28, 2009 09:22

Solution

There is one application in tanksloshing6Dof... named as genDof...
I have changed the file according to the need and then compile it by wmake..
and run this by typing file name genDof ... it generates a file named gendof.dat...
copy this to constant directory. It is working fi9...

thanks markc for the help...
:)

 liu.zhen December 15, 2009 03:56

I have same questions as markc ... hope someone can give the reference for so-called SDA.

And to lostin, it seems you succeed with the gendof.dat file to generate the motions of interest, did you validate the results by comparison with some analytical method or experiments?

 idrama February 12, 2011 16:19

Hello,

might anybody explain what effects each coefficient has?

 Terp March 31, 2011 13:22

I found this paper:
http://www.tfd.chalmers.se/~hani/kur...reeSurface.pdf

Which has some equations relating to the SDA constants, but it didn' make it very clear to me. :confused:

 binu April 22, 2011 21:46

i have also tried this genDof , its working and .dat extension file is created.
but i changed some data and save it . It showing error in dat file while rung the program.
How i can use other dat or different format data input file, as i have input tank motion in .xls(excel) format

 wolfindark September 16, 2011 16:24

Quote:
 Originally Posted by lostin4ever (Post 233849) I am trying to simulate tank sloshing problem in openfoam using interdyfoam solver and I am puzzled about the dynamicmeshdict file. I am not able to figure it out how we are giving the tank motion input? In my case I just need to do some horizontal displacement with a particular constant frequency (no rolling). Can you guide main in this regards? thanks in advance..
It is late answer but, you can use this for your problem dynamicMeshDict file. and run using interDyMFoam.

dynamicFvMesh solidBodyMotionFvMesh;

solidBodyMotionFvMeshCoeffs
{
solidBodyMotionFunction oscillatingLinearMotion;
oscillatingLinearMotionCoeffs
{
amplitude (0 0.1 0);
omega 5;
}
}

 jinheng October 23, 2012 23:07

Quote:
 Originally Posted by wolfindark (Post 324463) It is late answer but, you can use this for your problem dynamicMeshDict file. and run using interDyMFoam. dynamicFvMesh solidBodyMotionFvMesh; solidBodyMotionFvMeshCoeffs { solidBodyMotionFunction oscillatingLinearMotion; oscillatingLinearMotionCoeffs { amplitude (0 0.1 0); omega 5; } }
hello wolfindark,
i have used the oscillatingLinearMotion,just run the model and simulate the y-direction movement.but when i check my output data with the other papar ,it is not match. did you check you result? the omega is radian frequency ?right?
my case is 0.18*1*1m^3 rectangle tank filled 0.5m water and my amplitude is 0.005m,omega is 3.45rad/s which calc with w=sqrt(g*pi/l*tanh(pi*h/l))
thank you~

 wolfindark November 8, 2012 22:16

I checked my results with some analytically and fluent. They fits well

 jinheng November 8, 2012 23:55

Quote:
 Originally Posted by wolfindark (Post 391120) I checked my results with some analytically and fluent. They fits well

I am so happy to see your reply. I have found my fault. It is my frequency problem, and now it is very well. I have another question :
May I use the SDA to simulate the y-direction movement? just to change the roll and other movement to zero and just keep sway movement. Is that can work well? and did I need to change the dynamic function in SDA.C?

THANKS!

 musahossein September 4, 2013 21:34

pure translation of tank in interdymfoam, sloshingtank 2d

Dear members:

I would like to eliminate the roll and heave and leave only the sway, so that there is horizontal motion for the tank. However I would like to "hardcode" a simple sine formula into SDA.c to generate the horizontal translation only. Can anyone suggest how I can do this? i.e. find where the source code is and then modify the swayA formula to a simple sinusoidal formula. All the other coefficients will be set to zero.

Musa

 13msmemusman June 20, 2015 15:53

I need to find out values of rollA (Roll angle of tank) at every time step in interDyMFoam. i want to write then in a file but first thing is how to bring them in solver. please help. RollA is solved in SDA.C and SDA.H is included in InterDyMFoam.

 Tanak_Momogun April 19, 2016 02:11

Quote:
 Originally Posted by jinheng (Post 391125) I am so happy to see your reply. I have found my fault. It is my frequency problem, and now it is very well. I have another question : May I use the SDA to simulate the y-direction movement? just to change the roll and other movement to zero and just keep sway movement. Is that can work well? and did I need to change the dynamic function in SDA.C? THANKS!

I need some help, how do we set the frequency in Sloshing3DTank?

 musahossein May 2, 2016 21:19

I think rather than hard code any frequency or sine formula into OpenFoam, write a external code with the sine formula of you choice and modify the interDyMFoam/ras/sloshingtank3D/constant/3Dof.dat file. The external code should format the data as it is shown in the .dat file. Once the file has been generated you can run openfoam.

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