[eelcovv]

Dear All,

I started to explore the Lagrangian particle tracking capabilities of OF 2.1 last week. I would like to do particle tracking of non-reacting particles in an incompressible flow with turbulent dispersion. Standard forces like drag and buoyancy should be included. It seems that there is no standard model for this, as most models which come for OF are developed for reacting flows in compressible fluids. Therefore I tried to implement it myself. I have included the solver (pimpleCoupledKinematicParcelFOam ) + 2 test cases to this post. The solver works, except that I can not use the dispersionModels! I hope to find out what is wrong by opening this thread. First I will give some back ground of my approach and then I end with my question.

As a starting point I took the isoUncoupledKinematicParcelFoam solver in OF 2.1.0, which uses the kinematic particle foam class to solve the particle transport. As I understand, the particle tracking models in OF are all developed for compressible flow. This means that dt(rho,U) is solved in stead of dt(U), and moreover, the pressure is expressed in kg/m/s2 (Pa). The isoCoupledKinematicParcelFoam solver does not solve for U at all, so no problem here. However, I wanted to make a solver which also includes the U and p solution. If you formulate the solver as dt(rho,U), the turbulence modelling can not be included, because these require the pressure to have the unit m2/s2 (i.e. pressure normalized with density). Therefore I create a new pressure field p_rgh with units m2/s2 (just as the pimple solver), which I use in the solution of d(U)/dt and p_rgh, and calculate the p=rho*(rg+p_rgh) pressure which is the pressure in N/m2 including the hydrostatic pressure. This tricks works: you can include turbulence in the solution and still be able to call the kinematicParticle foam routines.

Well, here my version of the solver, which I call pimpleCoupledKinematicParcelFOam. It works and it allows you to use all functionality in the kinematic particles. It is actually very similar with the solver submitted michaelb in http://www.cfd-online.com/Forums/ope...-tracking.html, except that Michaels solver is only one-way coupled (it does not feed back the particle force on the fluid) and does not include the gravity term. So this solver is a bit more generic. I have taken Michaels test case of the 3D cavity with moving lid and show that the particle can be solved qualitatively correct. See the graph for a mass-less particle tracking and a particle with mass.

There is one problem which I can not solve though: if I want to use the dispesionModel in the kinematicParticleProperties dictionary, I get the following error:

lookup of RASProperties from objectRegistry region0 succesful, but is not RASModel, it is kEpsilon.

It seems to me that the dispersionModel again expects a turbulence model which is based on a compressible flow, whereas now in the solver the turbulence model is based on an incompressible flow.

My question is: can this be easily solved by tricking the dispersionModel, or do I need to rewrite the whole particle tracking class such that it is based on incompressible turbulence models?

Has somebody already implemented this Lagrangian particle tracing in transient incompressible flow which turbulent dispersion? Any hints or suggestions appreciated!

Regards
Eelco