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DIFFERENTIAL OPERATORS IN CURVILINEAR COORDINATES5 Cylindrical Coordinates Divergence ∇·A=

1 ∂ 1 ∂Aφ ∂Az (rAr ) + + r ∂r r ∂φ ∂z

Gradient (∇f )r =

∂f ; ∂r

(∇f )φ =

1 ∂f ; r ∂φ

(∇f )z =

Curl (∇ × A)r =

∂Aφ 1 ∂Az − r ∂φ ∂z

(∇ × A)φ =

∂Ar ∂Az − ∂z ∂r

(∇ × A)z =

1 ∂ 1 ∂Ar (rAφ ) − r ∂r r ∂φ

Laplacian 1 ∂ ∇ f = r ∂r 2



∂f r ∂r



+

1 ∂2f ∂2f + r 2 ∂φ2 ∂z 2

6

∂f ∂z

Laplacian of a vector 2

2

2

2

2

2

(∇ A)r = ∇ Ar −

(∇ A)φ = ∇ Aφ +

Ar 2 ∂Aφ − 2 2 r ∂φ r

Aφ 2 ∂Ar − 2 2 r ∂φ r

(∇ A)z = ∇ Az

Components of (A · ∇)B (A · ∇B)r = Ar

Aφ ∂Br Aφ B φ ∂Br ∂Br + + Az − ∂r r ∂φ ∂z r

(A · ∇B)φ = Ar

∂Bφ Aφ ∂Bφ ∂Bφ Aφ Br + + Az + ∂r r ∂φ ∂z r

(A · ∇B)z = Ar

Aφ ∂Bz ∂Bz ∂Bz + + Az ∂r r ∂φ ∂z

Divergence of a tensor (∇ · T )r =

Tφφ 1 ∂Tφr ∂Tzr 1 ∂ (rTrr ) + + − r ∂r r ∂φ ∂z r

(∇ · T )φ =

∂Tzφ Tφr 1 ∂ 1 ∂Tφφ (rTrφ ) + + + r ∂r r ∂φ ∂z r

(∇ · T )z =

1 ∂ 1 ∂Tφz ∂Tzz (rTrz ) + + r ∂r r ∂φ ∂z

7

Spherical Coordinates Divergence ∇·A=

∂Aφ 1 ∂ 1 1 ∂ 2 ) + ) + (r A (sin θA r θ r 2 ∂r r sin θ ∂θ r sin θ ∂φ

Gradient (∇f )r =

∂f ; ∂r

(∇f )θ =

1 ∂f ; r ∂θ

(∇f )φ =

1 ∂f r sin θ ∂φ

Curl (∇ × A)r =

∂ 1 ∂Aθ 1 (sin θAφ ) − r sin θ ∂θ r sin θ ∂φ

(∇ × A)θ =

∂Ar 1 ∂ 1 − (rAφ ) r sin θ ∂φ r ∂r

(∇ × A)φ =

1 ∂Ar 1 ∂ (rAθ ) − r ∂r r ∂θ

Laplacian 1 ∂ ∇ f = 2 r ∂r 2



∂f r ∂r 2



1 ∂ + 2 r sin θ ∂θ



∂f sin θ ∂θ



+

1 ∂2f r 2 sin2 θ ∂φ2

Laplacian of a vector 2

2

2

2

2

2

(∇ A)r = ∇ Ar −

(∇ A)θ = ∇ Aθ +

(∇ A)φ = ∇ Aφ −

∂Aφ 2Ar 2 ∂Aθ 2 cot θAθ 2 − − − r2 r 2 ∂θ r2 r 2 sin θ ∂φ

2 ∂Ar Aθ 2 cos θ ∂Aφ − − r 2 ∂θ r 2 sin2 θ r 2 sin2 θ ∂φ

Aφ 2 ∂Ar 2 cos θ ∂Aθ + + r 2 sin2 θ r 2 sin θ ∂φ r 2 sin2 θ ∂φ

8

Components of (A · ∇)B (A · ∇B)r = Ar

Aφ ∂Br Aθ B θ + Aφ B φ ∂Br Aθ ∂Br + + − ∂r r ∂θ r sin θ ∂φ r

(A · ∇B)θ = Ar

Aφ ∂Bθ cot θAφ Bφ ∂Bθ Aθ ∂Bθ Aθ Br + + + − ∂r r ∂θ r sin θ ∂φ r r

(A · ∇B)φ = Ar

∂Bφ Aφ ∂Bφ Aφ B r cot θAφ Bθ Aθ ∂Bφ + + + + ∂r r ∂θ r sin θ ∂φ r r

Divergence of a tensor (∇ · T )r =

1 ∂ 1 ∂ 2 (r Trr ) + (sin θTθr ) 2 r ∂r r sin θ ∂θ +

(∇ · T )θ =

1 ∂ 1 ∂ 2 (r Trθ ) + (sin θTθθ ) 2 r ∂r r sin θ ∂θ +

(∇ · T )φ =

∂Tφr Tθθ + Tφφ 1 − r sin θ ∂φ r

∂Tφθ cot θTφφ 1 Tθr + − r sin θ ∂φ r r

1 ∂ 1 ∂ 2 (r Trφ ) + (sin θTθφ ) 2 r ∂r r sin θ ∂θ +

9

∂Tφφ Tφr cot θTφθ 1 + + r sin θ ∂φ r r