Regarding modified drag force formulation for application in dense flows

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If you have a look into the classes defined in the folder "src/lagrangian/intermediate/submodels/Kinematic/ParticleForces",
there is an interesting pattern:

The sub-folder "ParticleForce" has the base class for all possible forces. It has 3 important methods:

Code:

//- Calculate the coupled force
virtual forceSuSp calcCoupled
(
const typename CloudType::parcelType& p,
const scalar dt,
const scalar mass,
const scalar Re,
const scalar muc
) const;

//- Calculate the non-coupled force
virtual forceSuSp calcNonCoupled
(
const typename CloudType::parcelType& p,
const scalar dt,
const scalar mass,
const scalar Re,
const scalar muc
) const;

//- Return the added mass
virtual scalar massAdd
(
const typename CloudType::parcelType& p,
const scalar mass
) const;

All rely in the class "forceSuSp", located in the sub-folder of the same name, which has the following description:

Quote:

Code: Helper container for force Su and Sp terms. F = Sp(U - Up) + Su Explicit contribution, Su specified as a force Implicit coefficient, Sp specified as force/velocity

For example, the sub-folder "Lift/LiftForce" has the base class structure for lift, which relies in the method "calcCoupled" and defines only the "Su" part and "Sp" is set to "0.0".
The sub-folder "Drag" has the classes for drag, from which you've pointed out "SphereDrag". These classes also rely in the method "calcCoupled" and defines only the "Sp" part.
The sub-folder "Gravity" has a single class that relies in the method "calcNonCoupled" and affects only "Su".
The class in the sub-folder "PressureGradient" also relies in the method "calcCoupled" and also affects "Su" only.
OK, so this gets us the individual accountabilities of each force component. The remaining question is: how are all
of them added up?
It's in the class "KinematicParcel", method "calcVelocity", located in the folder "src/lagrangian/intermediate/parcels/Templates/KinematicParcel/".
It relies on the class "TrackData::cloudType::forceType", where "TrackData" is a template name... OK, I got lost here, because this section is deeply based in templates, which is a considerable pain to figure out who-is-what-and-where-and-how 


But the point is that this line:

Code:

const forceSuSp Fcp = forces.calcCoupled(p, dt, mass, Re, mu);

is probably the addition of all forces that is listed inside "forces".

Hi ansu, Bruno,

I am also investigating this solver. I still have many remaining questions, but maybe the follwing gives you a starting
point:

A. For information on template for class Trackdata look into /intermediate/parcels/Templates/KinematicParcel/KinematicParcel.C.

B. If you want to include a new force to the solver, you may try the following (which I haven't tried yet):
Copy the intermediate library, recompile it to something like "mylib" in your user folder and link the new user library to your own copy of the solver (myIco... )
in submodels/Kinematic/ParticleForces/.. copy a drag model and rename it (do not forget to rename the classes inside the file)
In intermediate/parcels/include/makeParcelForces.H include the file "myNewForce.H" and add the force to the definition (register it to the library):

Code:

...
#include "myNewForce.H"

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

#define makeParcelForces(CloudType)                                           \
\
makeParticleForceModel(CloudType);                                        \
makeParticleForceModelType(myNewForce, CloudType);                   \
...

In the case file /constant/kinematicCloudProperties add

Code:

...
subModels
{
particleForces
{
sphereDrag;
gravity;
myNewForce;
}
...

I might find some time at the weekend to implement a new force and check if the works. I will keep you updated.