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Convective Operator


The convective operator associated with a vector field A is (A·del ), where del is the gradient operator.

Applied in a three-dimensional orthogonal coordinate system to a vector field B, the convective operator becomes

 [(A·del )B]_j=sum_(k=1)^3[(A_k)/(h_k)(partialB_j)/(partialq_k)+(B_k)/(h_kh_j)(A_j(partialh_j)/(partialq_k)-A_k(partialh_k)/(partialq_j))],
(1)

where A_i and B_i are physical components relative to the local orthonormal basis, and the scale factors h_i are related to the metric tensors by h_i=sqrt(g_(ii)) (Binney and Tremaine 2008, pp. 777-778). In Cartesian coordinates,

 (A·del )B=(A_x(partialB_x)/(partialx)+A_y(partialB_x)/(partialy)+A_z(partialB_x)/(partialz))x^^+(A_x(partialB_y)/(partialx)+A_y(partialB_y)/(partialy)+A_z(partialB_y)/(partialz))y^^+(A_x(partialB_z)/(partialx)+A_y(partialB_z)/(partialy)+A_z(partialB_z)/(partialz))z^^.
(2)

In cylindrical coordinates, with theta the azimuth,

 (A·del )B=(A_r(partialB_r)/(partialr)+(A_theta)/r(partialB_r)/(partialtheta)+A_z(partialB_r)/(partialz)-(A_thetaB_theta)/r)r^^+(A_r(partialB_theta)/(partialr)+(A_theta)/r(partialB_theta)/(partialtheta)+A_z(partialB_theta)/(partialz)+(A_thetaB_r)/r)theta^^+(A_r(partialB_z)/(partialr)+(A_theta)/r(partialB_z)/(partialtheta)+A_z(partialB_z)/(partialz))z^^.
(3)

In spherical coordinates, with theta the azimuth and phi the polar angle,

 (A·del )B=(A_r(partialB_r)/(partialr)+(A_phi)/r(partialB_r)/(partialphi)+(A_theta)/(rsinphi)(partialB_r)/(partialtheta)-(A_phiB_phi+A_thetaB_theta)/r)r^^
 +(A_r(partialB_phi)/(partialr)+(A_phi)/r(partialB_phi)/(partialphi)+(A_theta)/(rsinphi)(partialB_phi)/(partialtheta)+(A_phiB_r)/r-(A_thetaB_thetacotphi)/r)phi^^
 +(A_r(partialB_theta)/(partialr)+(A_phi)/r(partialB_theta)/(partialphi)+(A_theta)/(rsinphi)(partialB_theta)/(partialtheta)+(A_thetaB_r)/r+(A_thetaB_phicotphi)/r)theta^^.
(4)

See also

Convective Acceleration, Convective Derivative, Convective Term, Curvilinear Coordinates, Gradient

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References

Binney, J. and Tremaine, S. Galactic Dynamics, 2nd ed. Princeton, NJ: Princeton University Press, pp. 777-778, 2008. https://zakamska.johnshopkins.edu/FALL2019/binney_tremaine_appendixAB.pdf.

Referenced on Wolfram|Alpha

Convective Operator

Cite this as:

Weisstein, Eric W. "Convective Operator." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/ConvectiveOperator.html

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