[tayo]

Originally Posted by Hrushi

Hi Angelo & Tayo

Here is the updated version of baryCenter baryCenter-of201.zip utility. I have tested it on OpenFoam-201. You can comapre the each file in zip archive with one that you have to recognise the changes one needs to make it usable in OF201.

Hope it helps.

Regards
Hrushi

Thank you Hrushi. The hard job is done; It compiled fine. I simply ran the application after my simulation run time was complete and it printed out the value. Is there a way to extract the data from the barycenter into a file so that I won't have to manually copy the data? Have a nice weekend.

[Hrushi]

Hi,

Here is the updated version of baryCenter (for OF-2.2.1) baryCenter221.zip utility. I have tested it on OpenFOAM-2.2.1.

Enjoy!

[sfigato]

Dear Sebastian,

i want to compute the rise velocity. After you got your center file and you use it in Matlab, how do you compute exactely the rise velocity for each time step?

v(n-time) = ( barycentre(n) -barycentre (n-1) )/ deltaT

or

v(n-time) = ( barycentre(n) -barycentre (0) ) / ( t(n)- t (0) )

??

Thanks in advance

Marco

[Nazanin]

Originally Posted by Hrushi

Hi,

Here is the updated version of baryCenter (for OF-2.2.1) baryCenter221.zip utility. I have tested it on OpenFOAM-2.2.1.

Enjoy!

Hi Hrushikesh
Thank you for provide baryCenter..
But,how I can use this?I simulate rising bubble and I want calculate rising velocity,bubble diameter and surface area..but I don't know how define these??
can You help me??
Best

[arsalan.dryi]

Dear Foamers,

Is there a way to compute two or three bubbles center position an velocity with swak4Foam?!

I used a swakEpression as follows for calculating a single bubble center of position, but for two bubble, I don't have any idea!

    bubbleCentreY
    {
        type swakExpression;
        valueType internalField;
        verbose true;
    variables (
    "Vol= sum (alpha1 < 0.5 ? vol() : 0);"
    "VolY= sum (alpha1 < 0.5 ? pos().y*vol() : 0);"    
    );        
    expression "VolY/Vol";
        accumulations (
        min        
        );

     
    }

Thanks in advance,
Regards.

[18210436486]

Originally Posted by sega

My first setup was really bad.

I have done this now:
- used the complete computational domain (no symmetry)
- boundary-condition:
U: 0 at the bottom, zeroGradient at all other sides
pd: totalPressure 0 at the top, zeroGradient at all other sides
gamma: zeroGradient at all sides

I initialized the bubble as a sphere of defined radius and defined pressure inside.

All other transportProperties were chosen as in the literature mentioned above.

The simulation is running, but is not computing as I have planned.

- The bubble does not reach the "spherical cap sized" shape. It's more "skirted" at the sides.
Is that due to wall effects (actually there is no wall to the sides)?
Maybe I have to increade the computational domain?



The bubble is rising very slowly.
The image from above is after 30s Simulation time.
From the literature the bubble should reach its final shape and terminal velocity round about 0.1 Seconds ...

hi would you please tell me, how to make 2D region for bubble emerged in water using openfoam? I tried using setFeildsDic, but i do not know why it does not make a region...I am confused..it should be quit easy...

[sadra2003]

Hello Sebastian,

Thank you for the info you provided here.
I am also working on the terminal velocity of bubbles. Using the paraView, I measure the center of a bubble location in two successive time step, then by deviding the displacement of the center of bubble to the time difference, I wannt to calculate the velocity. The problem is, the value that I gain is 50 % lower than the reported values in the literature. I am using a 2D mesh in openFoam 8 using interFoam.
The contents of my 0 folder are:

U file:

dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
bottom
{
type noSlip;
}
outlet
{
type noSlip;
}
walls
{
type slip;
}
defaultFaces
{
type empty;
}
}


p_rgh file:
dimensions [1 -1 -2 0 0 0 0];

internalField uniform 0;

boundaryField
{
bottom
{
type zeroGradient;
}

outlet
{
type zeroGradient;
}

walls
{
type zeroGradient;
}

defaultFaces
{
type empty;
}
}

alpha file:


dimensions [0 0 0 0 0 0 0];

internalField uniform 0;

boundaryField
{
bottom
{
type zeroGradient;
}

outlet
{
type zeroGradient;
}

walls
{
type zeroGradient;
}

defaultFaces
{
type empty;
}
}


transportProperties file:

phases (air water);

air
{
transportModel Newtonian;
nu nu [ 0 2 -1 0 0 0 0 ] 1.5E-5;
rho rho [ 1 -3 0 0 0 0 0 ] 1.18;

}

water
{
transportModel Newtonian;
nu nu [ 0 2 -1 0 0 0 0 ] 7.22E-7;
rho rho [ 1 -3 0 0 0 0 0 ] 995.7;

}

Thanks a lot.

[piu58]

I simulated a similar case a few years agao. I did not look at the velocity but at they y value of the center of gravity, which is more or less the same. I get decent values only with veryl low values of maxCo, around 0.01.

[seju]

Originally Posted by sadra2003

Hello Sebastian,

Thank you for the info you provided here.
I am also working on the terminal velocity of bubbles. Using the paraView, I measure the center of a bubble location in two successive time step, then by deviding the displacement of the center of bubble to the time difference, I wannt to calculate the velocity. The problem is, the value that I gain is 50 % lower than the reported values in the literature. I am using a 2D mesh in openFoam 8 using interFoam.
The contents of my 0 folder are:

U file:

dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
bottom
{
type noSlip;
}
outlet
{
type noSlip;
}
walls
{
type slip;
}
defaultFaces
{
type empty;
}
}


p_rgh file:
dimensions [1 -1 -2 0 0 0 0];

internalField uniform 0;

boundaryField
{
bottom
{
type zeroGradient;
}

outlet
{
type zeroGradient;
}

walls
{
type zeroGradient;
}

defaultFaces
{
type empty;
}
}

alpha file:


dimensions [0 0 0 0 0 0 0];

internalField uniform 0;

boundaryField
{
bottom
{
type zeroGradient;
}

outlet
{
type zeroGradient;
}

walls
{
type zeroGradient;
}

defaultFaces
{
type empty;
}
}


transportProperties file:

phases (air water);

air
{
transportModel Newtonian;
nu nu [ 0 2 -1 0 0 0 0 ] 1.5E-5;
rho rho [ 1 -3 0 0 0 0 0 ] 1.18;

}

water
{
transportModel Newtonian;
nu nu [ 0 2 -1 0 0 0 0 ] 7.22E-7;
rho rho [ 1 -3 0 0 0 0 0 ] 995.7;

}

Thanks a lot.

You can see test cases and validations of different bubble regimes in this post:
Validation of Bubble Regime in Openfoam


#openFoam #bubble_velocity #validation #interFoam