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.

Thanks in advance,

Mark

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?

thanks in advance..

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...
:)

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?

Hello,

might anybody explain what effects each coefficient has?

Cheers in advance!

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:

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
Thanks in advnce

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;
}
}

reply
 

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~

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

thx for u reply
 

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!

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.

Thanks in advance.

Musa

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.

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

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.