[mechy]

Hi All
I want to solve perturbation equation with OF. I attached these equations.
but I don't know how to calculate the convection term. I used the bellow equation

fvVectorMatrix UperEqn
(
fvm::ddt(Uper)
+ fvc::grad(U)& Uper
+ fvc::grad(Uper)& U
- fvc::laplacian(nu, Uper)
);

solve(UperEqn == -fvc::grad(pper));


but OF debug encounter bellow error for calculating
fvc::grad(U)& Uper and fvc::grad(Uper)& U



error: no match for ‘operator+’ in ‘Foam::fvm::ddt(Foam::GeometricField<Type, Foam::fvPatchField, Foam::volMesh>&) [with Type = Foam::Vector<double>]() + Foam::fvc::grad(const Foam::GeometricField<Type, Foam::fvPatchField, Foam::volMesh>&) [with Type = Foam::Vector<double>]()’


I would be very appreciative if someone could point me in the right direction to get this model running.

[nimasam]

grad(U)& Uper
grad(Uper)& U =div (UUper)

so

fvVectorMatrix UperEqn
(
fvm::ddt(Uper)
+ fvm::div(phi,Uper)
+ fvm::laplacian(nu, Uper)
);

then
solve(UperEqn == -fvc::grad(pper));

[mechy]

since I want to remove the solving algebraic equation, I should calculate the derivative terms (like grad and laplacian) as an explicit fvc:: class
please see the attachment about perturbation equations and tell me how I can solve these equation with an fvc:: for all derivative and fvm:: for ddt()
in this equations U is defined and uper is undefined I want to calculate all derivative in the momentum equation with explicit manner except ddt().


Best Regards

[shouvik ghorui]

Have you found any suitable solution ?