[marialhm]

Dear all,

I need to do some programming in the Openfoam, but I'm not good at it. Now I need the equation shown in the attachment, but I don't know how to get the derivation over y. I think the command of fvc::grad() is to get the derivation over three directions, right?

Then how can I write the codes?

Many thanks.

Maria

[clapointe]

I think it will be :

 volScalarField u1u2 = u1*u2; //product of u1 and u2, assuming scalar fields
 volScalarField meanu1u2 = gSum(u1u2)/mesh.C().size(); // arithmetic mean of u1u2, assuming serial computation
 volScalarField Q = meanu1u2 /sigma // quantity, assuming all are scalars and you have defined volScalarFields for u1, u2, and sigma
 volVectorField gradQ = fvc::grad(Q); // gradient
 volScalarField gradQy = gradQ.component(1); // y component of gradQ

Caelan

[marialhm]

Originally Posted by clapointe

I think it will be :

 volScalarField u1u2 = u1*u2; //product of u1 and u2, assuming scalar fields
 volScalarField meanu1u2 = gSum(u1u2)/mesh.C().size(); // arithmetic mean of u1u2, assuming serial computation
 volScalarField Q = meanu1u2 /sigma // quantity, assuming all are scalars and you have defined volScalarFields for u1, u2, and sigma
 volVectorField gradQ = fvc::grad(Q); // gradient
 volScalarField gradQy = gradQ.component(1); // y component of gradQ

Caelan

Dear Caelan,

Many thanks for your help. I will try this.

Maria

[marialhm]

Originally Posted by clapointe

I think it will be :

 volScalarField u1u2 = u1*u2; //product of u1 and u2, assuming scalar fields
 volScalarField meanu1u2 = gSum(u1u2)/mesh.C().size(); // arithmetic mean of u1u2, assuming serial computation
 volScalarField Q = meanu1u2 /sigma // quantity, assuming all are scalars and you have defined volScalarFields for u1, u2, and sigma
 volVectorField gradQ = fvc::grad(Q); // gradient
 volScalarField gradQy = gradQ.component(1); // y component of gradQ

Caelan

Dear Caelan,

You mean that the type of u1, u2, and sigma must be volScalarField, right? What if they are scalars? Any possible way to do this?

Thanks.

Maria

[clapointe]

Yes, I meant volScalarField. I am not sure if it will work for a scalarField.

Caelan