- **OpenFOAM Bugs**
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- - **The LESModel for the family of LESmultiphase solvers**
(*https://www.cfd-online.com/Forums/openfoam-bugs/62417-lesmodel-family-lesmultiphase-solvers.html*)

Description:
I have dug into Description:
I have dug into the source behind the turbulence modeling for the family of LES-multiphase solvers. As I consider the general equation for turbulent kinetic energy, it includes rho, but in neither of the LES-multiphase solvers rho is part of the k-equations (I have only checked oneEqnEddy), but all uses incompressible formulation - even compressibleLesInterFoam. I believe that the turbulence equation for multiphase flows should take the density into consideration, thus a bug-fix would be to replace it with compressible flow equations. Solver/Application: The family of LES-multiphase solvers: - interPhaseChangeFoam - lesInterFoam - compressibleLesInterFoam - lesCavitatingFoam Source file: createFields.H in the above mentioned solvers. Testcase: None Platform: All Version: 1.5 Notes: |

I developed the current approaI developed the current approach to avoid spurious generation of turbulence at the interface where there may be a VERY large density gradient not associated with compressibility effects. To use compressible formulations of turbulence it would be better to use a fully two-phase formulation and solve for the momentum and turbulence properties of both phases, that way avoiding the issue of the density gradient at the interface.
H |

Hi Henry
Thanks for the rapHi Henry
Thanks for the rapid answer. I am curious, what do you mean by "fully two-phase formulation", because the momentum and turbulence equations are solved for both phases in e.g. lesInterFoam. Do you mean, that one should solve for the two phases separately with a clean interface? Thanks, Niels |

I mean solve momentum and turbI mean solve momentum and turbulence equations for both phases, i.e. two momentum equations and two sets of turbulence equations. The current family of VoF solvers use a "mixture" approach in which a single momentum equation and single set of turbulence equations are solved.
H |

Thanks,
Niels
Thanks,
Niels |

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