Inner product of a tensor and a vector in fvScalarMatrix

gxy200992243 · July 6, 2014, 14:39

Hi, everyone!

Now I want to express the equation below in fvScalarMatrix, where uj is a velocity vector, p is the pressure, and M is a constant Mach Number.

$M^2\frac{\partial p}{\partial t}+M^2u_j \frac{\partial p}{\partial x_j} + \frac{\partial u_j}{\partial x_j} = 0$

I wrote LHS of this equation in fvScalarMatrix as

Code:

fvm::ddt(p)+U & fvc::grad(p)+ fvc::div(U/M/M)

But the compiler told me:' const Foam::Vector<double>' is not derived from 'const Foam::dimensioned<Type>'

I think something must be wrong with my expression in fvScalarMatrix. Can anyone help me correct it?

I also want to know how to treat grad(p) implicitly. I have searched in the forum about implicit gradient for a long time, but I still cannot get the answer.

Billions of thanks,

Xiangyu

T.D. · October 13, 2014, 10:08

Hi,

Try:

fvm::ddt(p)+U & fvc::grad(p)+ pow(M,-2)*fvc::gGrad(U)

Pay attention for the dimensions too.

Good Luck !

Quote:

Originally Posted by gxy200992243

Hi, everyone!

Now I want to express the equation below in fvScalarMatrix, where uj is a velocity vector, p is the pressure, and M is a constant Mach Number.

$M^2\frac{\partial p}{\partial t}+M^2u_j \frac{\partial p}{\partial x_j} + \frac{\partial u_j}{\partial x_j} = 0$

I wrote LHS of this equation in fvScalarMatrix as

Code:

fvm::ddt(p)+U & fvc::grad(p)+ fvc::div(U/M/M)

But the compiler told me:' const Foam::Vector<double>' is not derived from 'const Foam::dimensioned<Type>'

I think something must be wrong with my expression in fvScalarMatrix. Can anyone help me correct it?

I also want to know how to treat grad(p) implicitly. I have searched in the forum about implicit gradient for a long time, but I still cannot get the answer.

Billions of thanks,

Xiangyu

July 6, 2014, 14:39	Inner product of a tensor and a vector in fvScalarMatrix	#1
gxy200992243 New Member Xiangyu Gao Join Date: Sep 2013 Location: West Lafayette, IN, USA Posts: 29 Rep Power: 13	Hi, everyone! Now I want to express the equation below in fvScalarMatrix, where uj is a velocity vector, p is the pressure, and M is a constant Mach Number. $M^2\frac{\partial p}{\partial t}+M^2u_j \frac{\partial p}{\partial x_j} + \frac{\partial u_j}{\partial x_j} = 0$ I wrote LHS of this equation in fvScalarMatrix as Code: fvm::ddt(p)+U & fvc::grad(p)+ fvc::div(U/M/M) But the compiler told me:' const Foam::Vector<double>' is not derived from 'const Foam::dimensioned<Type>' I think something must be wrong with my expression in fvScalarMatrix. Can anyone help me correct it? I also want to know how to treat grad(p) implicitly. I have searched in the forum about implicit gradient for a long time, but I still cannot get the answer. Billions of thanks, Xiangyu