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Tuesday, 7 October 2014

Seismic Tank Sloshing

This is a duplicated post from the forum of autodesk cfd simulation 

I work for a company that do simulations for oil tanks...In the last days we test CFD simulation because we wanted to do the simulation of sloshing of a tank when a seismic load is applied.
A natural frequency study is not enough for this simulations and we require a more precise simulation.

 As many people ask in the forum of how to setup free surface simulations and I believe that the tutorial of CFD is not clear enough.
I'm Going to explain how I did the simulation.
My first step was to get the accelerations in X,Y,Z for a specific earthquake.
I download the files from http://peer.berkeley.edu/smcat/search.html I suggest these files http://peer.berkeley.edu/svbin/Detail?id=P1083 you have to download the accelerations of UP,NS,EW they are equal to X,Y,Z.
The file are read from left to right and up to down with a time between measure of 0.005 second and the values are in g. to use this data in CFD it is need to translate the information into a simple column and mm/s3. I am attaching a small xls that i wrote to process the data.(to paste the data use the paste assistant of excel) I create the model in Inventor and exported to autodesk CFD.

I set the fluid as diesel.
I set the upper boundary as 0 pressure surface and the low volume as initial height of fluid.
Know we can setup the free space model.
Solve/physics/free surface

set the gravity in the direction you want in my case is 0,0,-1 and I set the tables of accelerations . The first step to set the tables is to save a blank file . that file is going to be your base *.csv file where you are going to paste the yellow data of my excel after editing that file in excel you can import the file to CFD
You have to do the same for all axis. place the files inside of the same folder of the design number in my case design 1 folder.
The time step size has to be less than 0.005 s or the simulations is not going to be good.

The only question that i couldn't solve is how to obtain a good surface mesh between the volumes i want a initial flat surface.
However the results are good



 

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