[ali_atrian]

Hello Dear openFOAMers
I am a bigginer to openFoam and I want to activate virtualMass force in solver icoLagrangianFoam. so in the file constant/kinematicCloudProperties I enable the force and also add a line to determine Cvm value:

particleForces
{
    gravity         on;
    virtualMass     on;
    Cvm	            0.5;
    pressureGradient on;
	
}

but I receive the error:

--> FOAM FATAL ERROR: 
Not implemented
    From function Foam::particleForces::calcCoupled(...) - virtual mass force
    in file particleForces/particleForces.C at line 153.
FOAM aborting
Aborted (core dumped)

the error is related to the following lines of src/lagrangian/intermediate/particleForces/particleForces.C:

Foam::vector Foam::particleForces::calcCoupled
(
    const label cellI,
    const scalar dt,
    const scalar rhoc,
    const scalar rho,
    const vector& Uc,
    const vector& U
) const
{
    vector Ftot = vector::zero;
    // Virtual mass force
    if (virtualMass_)
    {
        notImplemented
        (
            "Foam::particleForces::calcCoupled(...) - virtual mass force"
        );
//        Ftot += Cvm_*rhoc/rho*d(Uc - U)/dt;
    }

does anyone know what i ave to do?

I thankfuuullly apreciate any help

[ali_atrian]

some one give me just a small hint pleaseee
in file particleForces.C, I uncommented the line:

 Ftot += Cvm_*rhoc/rho*d(Uc - U)/dt

but I received the error:

particleForces/particleForces.C: In member function ‘Foam::vector Foam::particleForces::calcCoupled(Foam::label, Foam::scalar, Foam::scalar, Foam::scalar, const vector&, const vector&) const':
particleForces/particleForces.C:154:39: error: 'd' was not declared in this scope

what shoul i do? is there any toutorial shed lights on my problem
in openfoam 2.3 and 2.1 i didt find any library file including the virtual mass formula as included in foam-exd 3.0 and any other tutorials in foam extend 3.1 lead to the same errors when virtualMass" is "on"
I Greatfuuuly appreciate any help

[ali_atrian]

no help on virtual mass implemention to foam-exd 3.0??!!

[kalyan]

Hi,

even im struck with VIrtualMass. im using openFoam-2.3.x and defined VirtualMass in particle force as

virtualMass
{
Cvm 0.5;
}


but i get a error :

request for volVectorField U from objectRegistry region0 failed available objects of type volVectorField are 1(U.air).

if i remove virtualMass , then simualtion goes fine.. im not sure what this error is..


Regards,
Kalyan

[ali_atrian]

I got where the problem arises from:
I used "src/finiteVolume/finiteVolume/fvc" library and change the virtual mass formulation as:

Ftot += Cvm_*rhoc/rho*fvc::ddt(Uc-U);

but i found that all the class templates defined in fvcDdt.C have their output formats in something like volVectorField! :

    template<class Type>
    tmp<GeometricField<Type, fvPatchField, volMesh> > ddt
    (
        const GeometricField<Type, fvPatchField, volMesh>&
    );

while we need 'vector' format for 'Ftot' (in particleForces.C) :

Foam::vector Foam::particleForces::calcCoupled
(
    const label cellI,
    const scalar dt,
    const scalar rhoc,
    const scalar rho,
    const vector& Uc,
    const vector& U
) const
{
    vector Ftot = vector::zero;

so, we need to define a class template something like:

   /* template<class Type>
    tmp< vector > ddt
    (
        const vector&
    );
*/

and thats the way we can implement virtual mass force (I think so)
I myself have not ever defined any template so I neglected annny eddition because it seems hard for me to go through this way and now im going to simulate my problem using DPMFoam in OF230
however, I appreciate any comment whether on my findings or about template defenition for this problem
GoOoD LucK

[ali_atrian]

Originally Posted by kalyan

Hi,

even im struck with VIrtualMass. im using openFoam-2.3.x and defined VirtualMass in particle force as

virtualMass
{
Cvm 0.5;
}


but i get a error :

request for volVectorField U from objectRegistry region0 failed available objects of type volVectorField are 1(U.air).

if i remove virtualMass , then simualtion goes fine.. im not sure what this error is..


Regards,
Kalyan

I will be engaged in virtual mass force in OF230 so sooon, (as I mentioned in prior post) so I will talk about that if there be any comment to share with u

[oswald]

In order to calculate the virtual mass force, I added a new member to kinematicParcel called "Urelold". As the name suggests, it is the relative velocity between fluid and particle at the previous time step. To calculate d(Uc-Up)/dt, you can then use the old and the current relative velocities and the current time step and you don't need fvc::ddt(Uc-U) anymore.

[ali_atrian]

Hello Oswald
first of all i really thank you to give me some points
Maybe i can't get what you exactly mean, but :
1) here we nead (Uc-U) not an average between particle and fluid velocities!
2) in the formula, we have to insert the acceleration (not velocity) so why do you say

you can then use the old and the current relative velocities

?

- can u explane a bit more on code implementation (the code that u say it can be used instead of

fvc::ddt(Uc-U)

and does it need any other changes in any other files in libs or solver ??
Best Regards

[oswald]

I hope I got you right. The code fvc::ddt(Uc-U) can be seen as the change of the relative particle velocity (Uc-U) per time, i.e. d(Uc-U)/dt. Approximately this is the same as [(Uc-U)_current - (Uc-U)_old]/deltaT. (Uc-U)_current ist the current difference between particle and velocity fluid and can be calculated with the current values. I simply store this value as the value for (Uc-U)_old for the next time step. The change over time is then simply calculated by dividing the difference of the relative velocities by the current deltaT.

A disadvantage here is that you are not free to choose a different interpolation scheme.

The Urelold-value is stored in the kinematicParcel-class like U, d, rho and so on.

[ali_atrian]

Hello Oswald
I really appreciate all your guidance
Its now clear for me
Best Regards