Second boundary value problem

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One of the boundary value problems (cf. Boundary value problem, partial differential equations) for partial differential equations. For example, let there be given a second-order elliptic equation

\begin{equation} \label{f:1} Lu = \sum _ {i, j = 1 } ^ { n } a _ {ij} ( x)

\frac{\partial ^ {2} u ( x) }{\partial x _ {i} \partial x _ {j} }

+

\sum _ {i = 1 } ^ { n } b _ {i} ( x)

\frac{\partial u ( x) }{\partial x _ {i} }

+

c ( x) u ( x) = f ( x), \end{equation}

where $ x = ( x _ {1} \dots x _ {n} ) $, $ n \geq 2 $, in a bounded domain $ \Omega $, with a normal at each point of the boundary $ \Gamma $. The second boundary value problem for equation \eqref{f:1} in $ \Omega $ is the following problem: Out of the set of all solutions of equation \eqref{f:1}, isolate those solutions which have, at all boundary points, derivatives with respect to the interior normal $ N $ and which satisfy the condition

$$ \left . \frac{\partial u ( x, t) }{\partial N ( x) }

\right | _ {x \in \Gamma }

=  \phi ( x),

$$

where $ \phi ( x) $ is a given function. The second boundary value problem is also known as the Neumann problem.

References

[1] A.V. Bitsadze, "Boundary value problems for second-order elliptic equations" , North-Holland (1968) (Translated from Russian)
[2] V.S. Vladimirov, "Equations of mathematical physics" , MIR (1984) (Translated from Russian)
[3] C. Miranda, "Partial differential equations of elliptic type" , Springer (1970) (Translated from Italian)
[4] I.G. Petrovskii, "Partial differential equations" , Saunders (1967) (Translated from Russian)
[a1] P.R. Garabedian, "Partial differential equations" , Wiley (1963)
[a2] R. Courant, D. Hilbert, "Methods of mathematical physics. Partial differential equations" , 2 , Interscience (1965) (Translated from German)