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question on coefficient form PDE or general form PDE
Posted 03.09.2012, 03:57 GMT-4 Version 4.2, Version 4.2a 6 Replies
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c*del(deldotvelocity), where c is a constant and del is the del operator. Can anyone please suggest how to do this?
Thanks,
Regards,
Manish
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From what I see both your terms are just vectors with x and y components. But what is your conservation equation?
Suresh
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Example of an equation is attached.
Manish
Attachments:
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Your equation is confusing to me as it is mixed with scalars and vectors. To be specific, your LHS does not have a dot product, is this correct? The first and last term of your RHS is also a vector. Whereas the remaining term in the RHS is a scalar.
I may be wrong but you can check.
Suresh
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In the equation, u is a scalar and F is a vector. Sorry I had a typo in the WORD file where I said u and F are vectors.
Manish
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Sorry, I am still unable to help you. You still have mixed scalars and vectors in your conservation equation. You need to have scalars on both lhs and rhs of the equation. When you have u as a scalar, then grad(u) becomes a vector.
Perhaps you can send the original source of your equation.
Suresh
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First, I think you need another (constitutive? or conservative?) equation, or perhaps one of the variables (u?) is known a priori, or it's a function of the other.
Then I would expand your vector equation (let's suppose you apply it in Cartesian 3D) in 3 scalar equations, in the dependent variables (u?,) FX, FY and FZ.
Then define a coefficient form PDE (in 'Add Physics'/'Mathematics'/'PDE Interfaces') with those three or four dependent variables.
Finally you will have to identify the coefficients of COMSOL PDE equations as function of yours.
Bye.
Jesus.