Problems about the `eddyDissipation` model

[TimoLin]

Description

• Compiling problem If one want to use the eddyDisspation modek, the following thermo class should be modified:

From: https://github.com/deepmodeling/deepflame-dev/blob/1be82b637cd03ddcdbff61a140385c8a824a5ee2/applications/solvers/dfLowMachFoam/createFields.H#L7-L9 To:

 fluidThermo* pThermo = new heRhoThermo<rhoThermo, dfSingleStepReactingMixture>(mesh, word::null); 

• Simulation problem When the eddyDissipation model is set in combustionProperties, the simulation throws the following error:

[7] --> FOAM FATAL ERROR:
[7]
    lookup of turbulenceProperties from objectRegistry region0 successful
    but it is not a LES, it is a kEpsilon
[7]
[7]     From function const Type& Foam::objectRegistry::lookupObject(const Foam::word&) const [with Type = Foam::LESModel<Foam::EddyDiffusivity<Foam::ThermalDiffusivity<Foam::CompressibleTurbulenceModel<Foam::fluidThermo> > > >]
[7]     in file /public/home/chenzhi/dftorch/OpenFOAM-7/src/OpenFOAM/lnInclude/objectRegistryTemplates.C at line 178.
[7]
FOAM parallel run aborting

Releated code: https://github.com/deepmodeling/deepflame-dev/blob/1be82b637cd03ddcdbff61a140385c8a824a5ee2/src/dfCombustionModels/eddyDissipationModel/eddyDissipationModel.C#L93-L104

[TimoLin]

Possible fix patch

Use mesh.V()^{1/3} to calculate the delta directly?