finite area method, depth averaged model

Geb1313 · May 19, 2020, 13:38

Hi foamers,

I am developing (with a colleague) a depth average flow model for viscoplastic debris flow ( fluids with yield stress) based finite area method libraries. The flow model has a two years of the same material; layer 1, a shearing layer with hs and layer 2, plug layer with hp and the total depth of flow is h = hp+hs. One of the physical equation is:

$\frac{\partial U_p}{\partial t} + U_p . \nabla U_p + g \nabla h = g_s -\frac{ U_p}{|U_p|} \frac{ \tau_y}{\rho* h_p}$

I coded it as:
[/fam::ddt(Up)
+ Up & fac::grad(Up)
+ 1. 0/ rho * fam::Sp(tau0 / ((hp+h0)*(mag(Up) + u0)), Up)
]
And I got the following compiling error:
"
error: no match for ‘operator+’ (operand types are ‘Foam::tmp<Foam::GeometricField<Foam::Tensor<doubl e>, Foam::faPatchField, Foam::areaMesh> >’ and ‘Foam::tmp<Foam::faMatrix<Foam::Vector<double> > >’)
+ Up & fac::grad(Up)
~~~~~~~~~~~~~
+ 1. / rho * fam::Sp(tau0 / ((hp+h0)*(mag(Up) + u0)), Up)

error: no match for ‘operator+’ (operand types are ‘Foam::tmp<Foam::GeometricField<Foam::Tensor<doubl e>, Foam::faPatchField, Foam::areaMesh> >’ and ‘Foam::tmp<Foam::faMatrix<Foam::Vector<double> > >’)
+ Up & fac::grad(Up)
~~~~~~~~~~~~~
+ 1. / rho * fam::Sp(tau0 / ((hp+h0)*(mag(Up) + u0)), Up)

"
Is there any way to write $\ U_p . \nabla U_p$ in openfoam?

Geb1313 · May 19, 2020, 14:28

I tried to derive an alternative expression from:

$\nabla . U_p U_p =U_p .\nabla U_p +U_p(\nabla .U_p)$
Rearranging:
$U_p .\nabla U_p = \nabla . U_p U_p - U_p(\nabla .U_p)$

Then I coded it as:
[ fam::ddt(Up)
+ fam::div(phip, Up)
- fam::Sp(fac::div(phip), Up)
+ 1. / rho * fam::Sp(tau0 / ((hp+h0)*(mag(Up) + u0)), Up)
==
gs
- gn * fac::grad(h)]
where gn = g & n( normal) and gs = g -gn &n

The compilation went Ok. However a run on a trial case of 1D flume with inlet and outlet gave the following log:

"
Courant Number mean: 0.000277993 max: 0.000277993 velocity max magnitude: 0.0138996
deltaT = 0.000120482
Time = 0.000120482

DILUPBiCG: Solving for Upx, Initial residual = 1, Final residual = 1.53502e-17, No Iterations 1
DILUPBiCG: Solving for Upy, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Upz, Initial residual = 0, Final residual = 0, No Iterations 0

"
It stopped without warning. it couldn't continue to the next equation.

Any help please!

Thanks,

Gebray

May 19, 2020, 13:38	finite area method, depth averaged model	#1
Geb1313 New Member Join Date: Mar 2020 Posts: 16 Rep Power: 6	Hi foamers, I am developing (with a colleague) a depth average flow model for viscoplastic debris flow ( fluids with yield stress) based finite area method libraries. The flow model has a two years of the same material; layer 1, a shearing layer with hs and layer 2, plug layer with hp and the total depth of flow is h = hp+hs. One of the physical equation is: $\frac{\partial U_p}{\partial t} + U_p . \nabla U_p + g \nabla h = g_s -\frac{ U_p}{\|U_p\|} \frac{ \tau_y}{\rho* h_p}$ I coded it as: [/fam::ddt(Up) + Up & fac::grad(Up) + 1. 0/ rho * fam::Sp(tau0 / ((hp+h0)(mag(Up) + u0)), Up) ] And I got the following compiling error: " error: no match for ‘operator+’ (operand types are ‘Foam::tmp<Foam::GeometricField<Foam::Tensor<doubl e>, Foam::faPatchField, Foam::areaMesh> >’ and ‘Foam::tmp<Foam::faMatrix<Foam::Vector<double> > >’) + Up & fac::grad(Up) ~~~~~~~~~~~~~ + 1. / rho fam::Sp(tau0 / ((hp+h0)(mag(Up) + u0)), Up) error: no match for ‘operator+’ (operand types are ‘Foam::tmp<Foam::GeometricField<Foam::Tensor<doubl e>, Foam::faPatchField, Foam::areaMesh> >’ and ‘Foam::tmp<Foam::faMatrix<Foam::Vector<double> > >’) + Up & fac::grad(Up) ~~~~~~~~~~~~~ + 1. / rho fam::Sp(tau0 / ((hp+h0)*(mag(Up) + u0)), Up) " Is there any way to write $\ U_p . \nabla U_p$ in openfoam?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
interFoam wave propagation and explosion of Courant number and residuals	ChiaraViola	OpenFOAM Running, Solving & CFD	1	June 26, 2019 06:36
finite area method doesn't work in parallel (foam-extend-4.0)	andlog	OpenFOAM Bugs	8	December 11, 2017 12:04
The finite element method - “displacement” or “stiffness” method	3Lin7	ANSYS	0	February 15, 2013 19:36
The aspect ratio of the volume elements in Finite Volume Method	CharlieTan84	Main CFD Forum	3	August 28, 2012 03:34
finite volume method	co2	FLUENT	0	March 1, 2004 13:24

May 19, 2020, 14:28		#2
Geb1313 New Member Join Date: Mar 2020 Posts: 16 Rep Power: 6	I tried to derive an alternative expression from: $\nabla . U_p U_p =U_p .\nabla U_p +U_p(\nabla .U_p)$ Rearranging: $U_p .\nabla U_p = \nabla . U_p U_p - U_p(\nabla .U_p)$ Then I coded it as: [ fam::ddt(Up) + fam::div(phip, Up) - fam::Sp(fac::div(phip), Up) + 1. / rho * fam::Sp(tau0 / ((hp+h0)(mag(Up) + u0)), Up) == gs - gn fac::grad(h)] where gn = g & n( normal) and gs = g -gn &n The compilation went Ok. However a run on a trial case of 1D flume with inlet and outlet gave the following log: " Courant Number mean: 0.000277993 max: 0.000277993 velocity max magnitude: 0.0138996 deltaT = 0.000120482 Time = 0.000120482 DILUPBiCG: Solving for Upx, Initial residual = 1, Final residual = 1.53502e-17, No Iterations 1 DILUPBiCG: Solving for Upy, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Upz, Initial residual = 0, Final residual = 0, No Iterations 0 " It stopped without warning. it couldn't continue to the next equation. Any help please! Thanks, Gebray