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Trouble creating an injection pulse (interFoam)

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Old   September 28, 2012, 22:03
Default Trouble creating an injection pulse (interFoam)
  #1
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Greetings,

I am very new to OF. I've been using it for only a couple weeks now, and I'm runnning into some issues. I went through the interFoam/les/nozzleFlow2D tutorial (using OpenFOAM v2.1) and would like to make some changes to it. In the tutorial liquid is ejected from the nozzle through the entire simulation. I would like to change the model so only a short pulse of liquid is ejected from the nozzle. Basically, I would like to specify an injection duration. Does anyone have any thoughts on how I can accomplish this? I should also mention that I made one change to the tutorial. I wanted to specify the inlet using total pressure instead of velocity. Listed below is the code.

In 0/p_rgh ...

inlet
{
type totalPressure;
p0 1e6;
U U;
rho none;
phi phi;
psi none;
gamma 1;
value uniform 1e6
}

In 0/U ...

inlet
{
type pressureInletVelocity;
value uniform (0 0 0);
}

In addition, I tried to add a table to create the pulse of liquid but that didn't seem to work. Listed below is the code I used.

inlet
{
type uniformTotalPressure;
pressure table
(
(0 1e6)
(5e-6 0)
);
p0 1e6;
U U;
rho none;
phi phi;
psi none;
gamma 1;
value uniform 1e6
}

Thank you!
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Old   October 10, 2012, 05:52
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Michiel
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You could use something like this:

Code:
inlet
    {   
        type            uniformFixedValue;
        uniformValue    table 
        (    
                (0      (0.05 0 0)) 
                (0.05   (0.05 0 0)) 
                (0.1    (0 0 0)) 
        );    
    }
That will give you an x-velocity of 0.05 m/s from t=0 to t=0.05 which then decreases linearly to 0 from t=0.05 to t=0.1
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Old   October 10, 2012, 12:26
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Quote:
Originally Posted by michielm View Post
You could use something like this:

Code:
inlet
    {   
        type            uniformFixedValue;
        uniformValue    table 
        (    
                (0      (0.05 0 0)) 
                (0.05   (0.05 0 0)) 
                (0.1    (0 0 0)) 
        );    
    }
That will give you an x-velocity of 0.05 m/s from t=0 to t=0.05 which then decreases linearly to 0 from t=0.05 to t=0.1

Thank you so much! That's exactly what I was looking for.

Thanks again,
Scott
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