Nabla în coordonate cilindrice și sferice
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În calculul vectorial este adesea util să știi să exprimi {\ displaystyle \ nabla} în alte sisteme de coordonate, altele decât cel cartezian .
Operator | Coordonatele carteziene (x, y, z) | Coordonate cilindrice (ρ, φ, z) | Coordonate sferice (r, θ, φ) |
---|---|---|---|
Definirea coordonatelor | {\ displaystyle {\ begin {cases} x & = & \ rho \ cos \ phi \\ y & = & \ rho \ sin \ phi \\ z & = & z \ end {cases}}} | {\ displaystyle {\ begin {cases} x & = & r \ sin \ theta \ cos \ phi & 0 \ leqslant \ theta \ leqslant \ pi \\ y & = & r \ sin \ theta \ sin \ phi & 0 \ leqslant \ phi <2 \ pi \\ z & = & r \ cos \ theta & 0 \ leqslant r <+ \ infty \\\ end {cases}}} | |
{\ displaystyle {\ begin {cases} \ rho & = & {\ sqrt {x ^ {2} + y ^ {2}}} \\\ phi & = & \ arctan (y / x) \\ z & = & z \ end {cases}}} | {\ displaystyle {\ begin {cases} r & = & {\ sqrt {x ^ {2} + y ^ {2} + z ^ {2}}} \\\ theta & = & \ arccos (z / r) \ \\ phi & = & \ arctan (y / x) \ end {cases}}} | ||
Câmpul vector {\ displaystyle \ mathbf {A}} | {\ displaystyle A_ {x} \ mathbf {\ hat {x}} + A_ {y} \ mathbf {\ hat {y}} + A_ {z} \ mathbf {\ hat {z}}} | {\ displaystyle A _ {\ rho} {\ boldsymbol {\ hat {\ rho}}} + A _ {\ phi} {\ boldsymbol {\ hat {\ phi}}} + A_ {z} {\ boldsymbol {\ pălărie {z}}}} | {\ displaystyle A_ {r} {\ boldsymbol {\ hat {r}}} + A _ {\ theta} {\ boldsymbol {\ hat {\ theta}}} + A _ {\ phi} {\ boldsymbol {\ hat {\ phi}}}} |
Gradient {\ displaystyle \ nabla f} | {\ displaystyle {\ partial f \ over \ partial x} \ mathbf {\ hat {x}} + {\ partial f \ over \ partial y} \ mathbf {\ hat {y}} + {\ partial f \ over \ parțial z} \ mathbf {\ hat {z}}} | {\ displaystyle {\ partial f \ over \ partial \ rho} {\ boldsymbol {\ hat {\ rho}}} + {1 \ over \ rho} {\ partial f \ over \ partial \ phi} {\ boldsymbol {\ hat {\ phi}}} + {\ partial f \ over \ partial z} {\ boldsymbol {\ hat {z}}}} | {\ displaystyle {\ partial f \ over \ partial r} {\ boldsymbol {\ hat {r}}} + {1 \ over r} {\ partial f \ over \ partial \ theta} {\ boldsymbol {\ hat {\ theta}}} + {1 \ over r \ sin \ theta} {\ partial f \ over \ partial \ phi} {\ boldsymbol {\ hat {\ phi}}}} |
Divergenţă {\ displaystyle \ nabla \ cdot \ mathbf {A}} | {\ displaystyle {\ partial A_ {x} \ over \ partial x} + {\ partial A_ {y} \ over \ partial y} + {\ partial A_ {z} \ over \ partial z}} | {\ displaystyle {1 \ over \ rho} {\ partial (\ rho A _ {\ rho}) \ over \ partial \ rho} + {1 \ over \ rho} {\ partial A _ {\ phi} \ over \ partial \ phi} + {\ partial A_ {z} \ over \ partial z}} | {\ displaystyle {1 \ over r ^ {2}} {\ partial (r ^ {2} A_ {r}) \ over \ partial r} + {1 \ over r \ sin \ theta} {\ partial \ over \ partial \ theta} (A _ {\ theta} \ sin \ theta) + {1 \ over r \ sin \ theta} {\ partial A _ {\ phi} \ over \ partial \ phi}} |
Rotor {\ displaystyle \ nabla \ times \ mathbf {A}} | {\ displaystyle {\ begin {matrix} \ displaystyle {\ bigg (} {\ partial A_ {z} \ over \ partial y} - {\ partial A_ {y} \ over \ partial z} {\ bigg)} \ mathbf {\ hat {x}} & + \\\ displaystyle {\ bigg (} {\ partial A_ {x} \ over \ partial z} - {\ partial A_ {z} \ over \ partial x} {\ bigg)} \ mathbf {\ hat {y}} & + \\\ displaystyle {\ bigg (} {\ partial A_ {y} \ over \ partial x} - {\ partial A_ {x} \ over \ partial y} {\ bigg )} \ mathbf {\ hat {z}} & \ \ end {matrix}}} | {\ displaystyle {\ begin {matrix} \ displaystyle {\ bigg (} {1 \ over \ rho} {\ partial A_ {z} \ over \ partial \ phi} - {\ partial A _ {\ phi} \ over \ partial z} {\ bigg)} {\ boldsymbol {\ hat {\ rho}}} & + \\\ displaystyle {\ bigg (} {\ partial A _ {\ rho} \ over \ partial z} - {\ partial A_ {z} \ over \ partial \ rho} {\ bigg)} {\ boldsymbol {\ hat {\ phi}}} & + \\\ displaystyle {1 \ over \ rho} {\ bigg (} {\ partial ( \ rho A _ {\ phi}) \ over \ partial \ rho} - {\ partial A _ {\ rho} \ over \ partial \ phi} {\ bigg)} {\ boldsymbol {\ hat {z}}} & \ \ end {matrix}}} | {\ displaystyle {\ begin {matrix} \ displaystyle {1 \ over r \ sin \ theta} {\ bigg (} {\ partial \ over \ partial \ theta} (A _ {\ phi} \ sin \ theta) - { \ partial A _ {\ theta} \ over \ partial \ phi} {\ bigg)} {\ boldsymbol {\ hat {r}}} & + \\\ displaystyle {1 \ over r} {\ bigg (} {1 \ over \ sin \ theta} {\ partial A_ {r} \ over \ partial \ phi} - {\ partial \ over \ partial r} (rA _ {\ phi}) {\ bigg)} {\ boldsymbol {\ hat {\ theta}}} & + \\\ displaystyle {1 \ over r} {\ bigg (} {\ partial \ over \ partial r} (rA _ {\ theta}) - {\ partial A_ {r} \ over \ partial \ theta} {\ bigg)} {\ boldsymbol {\ hat {\ phi}}} & \ \ end {matrix}}} |
Laplacian {\ displaystyle \ nabla ^ {2} f} | {\ displaystyle {\ partial ^ {2} f \ over \ partial x ^ {2}} + {\ partial ^ {2} f \ over \ partial y ^ {2}} + {\ partial ^ {2} f \ peste \ partial z ^ {2}}} | {\ displaystyle {1 \ over \ rho} {\ partial \ over \ partial \ rho} {\ bigg (} \ rho {\ partial f \ over \ partial \ rho} {\ bigg)} + {1 \ over \ rho ^ {2}} {\ partial ^ {2} f \ over \ partial \ phi ^ {2}} + {\ partial ^ {2} f \ over \ partial z ^ {2}}} | {\ displaystyle {1 \ over r ^ {2}} {\ partial \ over \ partial r} {\ bigg (} r ^ {2} {\ partial f \ over \ partial r} {\ bigg)} + {1 \ over r ^ {2} \ sin \ theta} {\ partial \ over \ partial \ theta} {\ bigg (} \ sin \ theta {\ partial f \ over \ partial \ theta} {\ bigg)} + {1 \ over r ^ {2} \ sin ^ {2} \ theta} {\ partial ^ {2} f \ over \ partial \ phi ^ {2}}} |
Laplacian al unui vector {\ displaystyle \ nabla ^ {2} \ mathbf {A}} | {\ displaystyle \ nabla ^ {2} A_ {x} \ mathbf {\ hat {x}} + \ nabla ^ {2} A_ {y} \ mathbf {\ hat {y}} + \ nabla ^ {2} A_ {z} \ mathbf {\ hat {z}}} | {\ displaystyle {\ begin {matrix} \ displaystyle {\ bigg (} \ nabla ^ {2} A _ {\ rho} - {A _ {\ rho} \ over \ rho ^ {2}} - {2 \ over \ rho ^ {2}} {\ partial A _ {\ phi} \ over \ partial \ phi} {\ bigg)} {\ boldsymbol {\ hat {\ rho}}} & + \\\ displaystyle {\ bigg ( } \ nabla ^ {2} A _ {\ phi} - {A _ {\ phi} \ over \ rho ^ {2}} + {2 \ over \ rho ^ {2}} {\ partial A _ {\ rho } \ over \ partial \ phi} {\ bigg)} {\ boldsymbol {\ hat {\ phi}}} & + \\\ displaystyle (\ nabla ^ {2} A_ {z}) {\ boldsymbol {\ hat { z}}} & \ \ end {matrix}}} | {\ displaystyle {\ begin {matrix} {\ bigg (} \ nabla ^ {2} A_ {r} - {2A_ {r} \ over r ^ {2}} - {2 \ over r ^ {2} \ sin \ theta} {\ partial (A _ {\ theta} \ sin \ theta) \ over \ partial \ theta} - {2 \ over r ^ {2} \ sin \ theta} {\ partial A _ {\ phi} \ over \ partial \ phi} {\ bigg)} {\ boldsymbol {\ hat {r}}} & + \\ {\ bigg (} \ nabla ^ {2} A _ {\ theta} - {A _ {\ theta } \ over r ^ {2} \ sin ^ {2} \ theta} + {2 \ over r ^ {2}} {\ partial A_ {r} \ over \ partial \ theta} - {2 \ cos \ theta \ over r ^ {2} \ sin ^ {2} \ theta} {\ partial A _ {\ phi} \ over \ partial \ phi} {\ bigg)} {\ boldsymbol {\ hat {\ theta}}} & + \\ {\ bigg (} \ nabla ^ {2} A _ {\ phi} - {A _ {\ phi} \ over r ^ {2} \ sin ^ {2} \ theta} + {2 \ over r ^ {2} \ sin \ theta} {\ partial A_ {r} \ over \ partial \ phi} + {2 \ cos \ theta \ over r ^ {2} \ sin ^ {2} \ theta} {\ partial A _ {\ theta} \ over \ partial \ phi} {\ bigg)} {\ boldsymbol {\ hat {\ phi}}} & \ end {matrix}}} |
Lungime infinitesimală | {\ displaystyle d \ mathbf {l} = dx \ mathbf {\ hat {x}} + dy \ mathbf {\ hat {y}} + dz \ mathbf {\ hat {z}}} | {\ displaystyle d \ mathbf {l} = d \ rho {\ boldsymbol {\ hat {\ rho}}} + \ rho d \ phi {\ boldsymbol {\ hat {\ phi}}} + dz {\ boldsymbol {\ pălărie {z}}}} | {\ displaystyle d \ mathbf {l} = dr \ mathbf {\ hat {r}} + rd \ theta {\ boldsymbol {\ hat {\ theta}}} + r \ sin \ theta d \ phi {\ boldsymbol {\ pălărie {\ phi}}}} |
Zonele infinitesimale | {\ displaystyle {\ begin {matrix} d \ mathbf {S} = & dydz \ mathbf {\ hat {x}} + \\ & dxdz \ mathbf {\ hat {y}} + \\ & dxdy \ mathbf {\ pălărie {z}} \ end {matrix}}} | {\ displaystyle {\ begin {matrix} d \ mathbf {S} = & \ rho d \ phi dz {\ boldsymbol {\ hat {\ rho}}} + \\ & d \ rho dz {\ boldsymbol {\ hat { \ phi}}} + \\ & \ rho d \ rho d \ phi \ mathbf {\ hat {z}} \ end {matrix}}} | {\ displaystyle {\ begin {matrix} d \ mathbf {S} = & r ^ {2} \ sin \ theta d \ theta d \ phi \ mathbf {\ hat {r}} + \\ & r \ sin \ theta drd \ phi {\ boldsymbol {\ hat {\ theta}}} + \\ & rdrd \ theta {\ boldsymbol {\ hat {\ phi}}} \ end {matrix}}} |
Volumul infinitesimal | {\ displaystyle dv = dxdydz} | {\ displaystyle dv = \ rho d \ rho d \ phi dz} | {\ displaystyle dv = r ^ {2} \ sin \ theta drd \ theta d \ phi} |
Relații notabile (valabile în toate sistemele de referință): care împreună cu {\ displaystyle \ mathbf {A} = \ mathbf {B} = \ mathbf {v}} Cheia fluidului de transformare mecanică Weber urmează imediat: {\ displaystyle (\ mathbf {v} \ cdot \ nabla) \ mathbf {v} = \ nabla {\ frac {\ mathbf {v} ^ {2}} {2}} - \ mathbf {v} \ times (\ nabla \ times \ mathbf {v})} |
Notă
- Funcția atan2 (y, x) este utilizată în locul arctan (y / x) pentru domeniul său. Funcția arctan (y / x) are imagine în (-π / 2, + π / 2), în timp ce atan2 (y, x) are imagine în (-π, π].
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