Definition:Orthogonal Curvilinear Coordinates/Definition 1
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Definition
Let $\KK$ be a curvilinear coordinate system in $3$-space.
Let $\QQ_1$, $\QQ_2$ and $\QQ_3$ denote the one-parameter families that define the curvilinear coordinates.
Let the relation between those curvilinear coordinates and Cartesian coordinates be expressed as:
\(\ds x\) | \(=\) | \(\ds \map x {q_1, q_2, q_3}\) | ||||||||||||
\(\ds y\) | \(=\) | \(\ds \map y {q_1, q_2, q_3}\) | ||||||||||||
\(\ds z\) | \(=\) | \(\ds \map z {q_1, q_2, q_3}\) |
where:
- $\tuple {x, y, z}$ denotes the Cartesian coordinates of an arbitrary point $P$
- $\tuple {q_1, q_2, q_3}$ denotes the curvilinear coordinates of $P$.
Let these equations have the property that the metric of $\KK$ between coordinate surfaces of $\QQ_i$ and $\QQ_j$ is zero where $i \ne j$.
That is, for every point $P$ expressible as $\tuple {x, y, z}$ and $\tuple {q_1, q_2, q_3}$:
- $\dfrac {\partial x} {\partial q_i} \dfrac {\partial x} {\partial q_j} + \dfrac {\partial y} {\partial q_i} \dfrac {\partial y} {\partial q_j} + \dfrac {\partial z} {\partial q_i} \dfrac {\partial z} {\partial q_j} = 0$
wherever $i \ne j$.
Then $\KK$ is an orthogonal curvilinear coordinate system.
Also see
- Results about orthogonal curvilinear coordinates can be found here.
Sources
- 1961: Ian N. Sneddon: Special Functions of Mathematical Physics and Chemistry (2nd ed.) ... (previous) ... (next): Chapter $\text I$: Introduction: $\S 1$. The origin of special functions
- 1970: George Arfken: Mathematical Methods for Physicists (2nd ed.) ... (previous) ... (next): Chapter $2$ Coordinate Systems $2.1$ Curvilinear Coordinates: $(2.6)$