FGρ=sinθcosφFρGρρsinθcosφ+GθρcosθcosφGφρsinφ+FθρGρθsinθcosφ+Gρcosθcosφ+GθθcosθcosφGθsinθcosφGφθsinφ+FφsinθρGρφsinθcosφGρsinθsinφ+GθφcosθcosφGθcosθsinφGφφsinφGφcosφ+sinθsinφFρGρρsinθsinφ+Gθρcosθsinφ+Gφρcosφ+FθρGρθsinθsinφ+Gρcosθsinφ+GθθcosθsinφGθsinθsinφ+Gφθcosφ+FφsinθρGρφsinθsinφ+Gρsinθcosφ+Gθφcosθsinφ+Gθcosθcosφ+GφφcosφGφsinφ+cosθFρGρρcosθGθρsinθ+FθρGρθcosθGρsinθGθθsinθGθcosθ+FφsinθρGρφcosθGθφsinθ=FρGρρsin2θcos2φ+Gθρsinθcosθcos2φGφρsinθsinφcosφ+FθρGρθsin2θcos2φ+Gρsinθcosθcos2φ+Gθθsinθcosθcos2φGθsin2θcos2φGφθsinθsinφcosφ+FφsinθρGρφsin2θcos2φGρsin2θsinφcosφ+Gθφsinθcosθcos2φGθsinθcosθsinφcosφGφφsinθsinφcosφGφsinθcos2φ+FρGρρsin2θcos2φ+Gθρsinθcosθsin2φ+Gφρsinθsinφcosφ+FθρGρθsin2θsin2φ+Gρcosθsinθsin2φ+Gθθsinθcosθsin2φGθsin2θsin2φGφθsinθsinφcosφ+FφsinθρGρφsin2θsin2φ+Gρsin2θsinφcosφ+Gθφsinθcosθsin2φ+Gθsinθcosθsinφcosφ+GφφsinθsinφcosφGφsinθsin2φ+FρGρρcos2θGθρsinθcosθ+FθρGρθcos2θGρsinθcosφGθθsinθcosθGθcos2θ+FφsinθρGρφcos2θGθφsinθcosθ=FρGρρ+FθρGρθ+FφρsinθGρφFθGθ+FφGφρ

si410_e  (Eq. 7.140)

Proceeding likewise for the θ -component we find

FGθ=cosθcosφFρGρρsinθcosφ+GθρcosθcosφGφρsinφ+FθρGρθsinθcosφ+Gρcosθcosφ+GθθcosθcosφGθsinθcosφGφθsinφ+FφsinθρGρφsinθcosφGρsinθsinφ+GθφcosθcosφGθcosθsinφGφφsinφGφcosφ+sinφcosθFρGρρsinθsinφ+Gθρcosθsinφ+Gφρcosφ+FθρGρθsinθsinφ+Gρcosθsinφ+GθθcosθsinφGθsinθsinφ+Gφθcosφ+FφsinθρGρφsinθsinφ+Gρsinθcosφ+Gθφcosθsinφ+Gθcosθcosφ+GφφcosφGφsinφsinθFρGρρcosθGθρsinθ+FθρGρθcosθGρsinθGθθsinθGθcosθ+FφsinθρGρφcosθGθφsinθ=FρGρρsinθcosθcos2φ+Gθρcos2θcos2φGφρcosθsinφcosφ+FθρGρθsinθcosθcos2φ+Gρcos2θcos2φ+Gθθcos2θcos2φGθsinθcosθcos2φGφθcosθsinφcosφ+FφsinθρGρφsinθcosθcos2φGρsinθcosθsinφcosφ+Gθφcos2θcos2φGθcos2θsinφcosφGφφcosθsinφcosφGφcosθcos2φ)+FρGρρsinθcosθsin2φ+Gθρcos2θsin2φ+Gφρcosθsinφcosφ+FθρGρθsinθcosθsin2φ+Gρcos2θsin2φ+Gθθcos2θsin2φGθsinθcosθsin2φ+Gφθcosθsinφcosφ+FφsinθρGρφsinθcosθsin2φ+Gρsinθcosθsinφcosφ+Gθφcos2θsin2φ+Gθcos2θsinφcosφ+GφφcosθsinφcosφGφcosθsin2φ)FρGρρsinθcosθGθρsin2θFθρGρθsinθcosθGρsin2θGθθsin2θGθsinθcosθFφsinθρGρφsinθcosθGθφsin2θ=FρGθρ+FθρGθθ+FφρsinθGθφFθGρρFφGφρcosθsinθ

si411_e  (Eq. 7.141)

Finally we find for the φ -component

FGθ=sinφFρGρρsinθcosφ+GθρcosθcosφGφρsinφ+FθρGρθsinθcosφ+Gρcosθcosφ+GθθcosθcosφGθsinθcosφGφθsinφ+FφsinθρGρφsinθcosφGρsinθsinφ+GθφcosθcosφGθcosθsinφGφφsinφGφcosφ+cosφFρGρρsinθsinφ+Gθρcosθsinφ+Gφρcosφ+FθρGρθsinθsinφ+Gρcosθsinφ+GθθcosθsinφGθsinθsinφ+Gφθcosφ+FφsinθρGρφsinθsinφ+Gρsinθcosφ+Gθφcosθsinφ+Gθcosθcosφ+GφφcosφGφsinφ=FρGρρsinθsinφcosφ+GθρcosθsinφcosφGφρsin2φFθρGρθsinθsinφcosφ+Gρcosθsinφcosφ+GθθcosθsinφcosφGθsinθsinφcosφGφθsin2φFφsinθρGρφsinθsinφcosφGρsinθsin2φ+GθφcosθsinφcosφGθcosθsin2φGφφsin2φGφsinφcosφ+FρGρρsinθsinφcosφ+Gθρcosθsinφcosφ+Gφρcos2φ+FθρGρθsinθsinφcosφ+Gρcosθsinφcosφ+GθθcosθsinφcosφGθsinθcosφcosφ+Gφθcos2φ+FφsinθρGρφsinθsinφcosφ+Gρsinθcos2φ+Gθφcosθsinφcosφ+Gθcosθcos2φ+Gφφcos2φGφsinφcosφ=FρGφρ+FθρGφθ+FφρsinθGφφ+FφGρρ+FφGθρcosθsinθ

si412_e  (Eq. 7.142)

Reassembling Eq. 7.140, Eq. 7.141, and Eq. 7.142 yields the material derivative in cylindrical coordinates given by

FG=FρGρρ+FθρGρθ+FφρsinθGρφFθGθ+FφGφρeρ+FρGθρ+FθρGθθ+FφρsinθGθφ+FθGρρFφGφρcosθsinθeθ+FρGφρ+FθρGφθ+FφρsinθGφφ+FφGρρ+FφGθρcosθsinθeφ

si413_e  (Eq. 7.143)

7.7 Summary

In this section we have studied the fundamental concepts of vector calculus and introduced the most important operators. We also introduced the four important theorems of vector calculus, i.e., the theorems of Gauß, Stokes, and Green, as well as Reynolds’ transport theorem. In addition, we studied the four di˙erent coordinate systems that we require for solving fluid mechanical problems in di˙erent geometries. As we will see, the equations often become significantly simpler when transferred into the right coordinate system. Besides position, velocity, and acceleration vectors, we have also derived the most important operators in the respective coordinate systems. Once we have established the fundamental equations of fluid mechanics, it will be very easy to convert them to the appropriate coordinate system using the equations we set up in this section.

References

[1] Green G. An essay on the application of mathematical analysis to the theories of electricity and magnetism. 1828 (cit. on pp. 143, 145).

[2] Challis L., Sheard F. The green of green functions. no. 12 In: Physics Today. 41–46. 2003;vol. 56 (cit. on p. 143).

[3] Gauss C.F. Theoria Attractionis Corporum Sphaeroidicorum Ellipticorum Homogeneorum. Springer; 1877 (cit. on p. 143).

[4] Stokes S.G.G., et al. Mathematical and physical papers. 1901 (cit. on p. 144).

[5] Reynolds O. An experimental investigation of the circumstances which determine whether the motion of water shall be direct or sinuous, and of the law of resistance in parallel channels. no. 224–226 In: Proceedings of the Royal Society of London; 84–99. 1883;vol. 35 (cit. on p. 145).

[6] Reynolds O., Brightmore A.W., Moorby W.H. The Sub-mechanics of the Universe. In: University Press; . 1903;Vol. 3 (cit. on p. 145).

[7] Jordan C. Traité des substitutions et des équations algébriques. Gauthier-Villars; 1870 (cit. on p. 158).


1 Carl Gauß was a German mathematician and ranks among the most important mathematician of all time. The Gauß-Jordan algorithm for solving systems of linear equations carries his name, although he did not invent or introduce it. Gauß himself is said to have stated that this method was “commonly known”.

2 George Green was a British self-taught scientist. He received only very little formal training. Therefore one may consider him to be a physician or a mathematician. Among other things, he was a miller, a baker, and a librarian. He published a very important essay in 1828 which introduced the concept of the Green’s function which is one of the most important concepts for deriving general solutions to inhomogeneous differential equations [1]. For a very fun read about the life, work, and importance of Green the reader may refer to [2].

1 Osborne Reynolds was an Irish engineer who made important contributions to fluid mechanics. He is credited with the first experimental accounts of the transition of laminar to turbulent flow that he published in 1883 [5]. Reynolds made numerous experimental contributions to the literature studying turbulent flows and its impact on pipe systems and vessels, both theoretically and practically. A very important theorem provided by him is the Reynolds transport theorem which he first described in 1903 [6]. The Reynolds number (see section 9.9.8) is coined after him.

1 Camille Jordan was a French mathematician who made important contributions to the mathematics of linear algebra. His name is associated with the Gauß-Jordan algorithm for solving linear systems of equations. Just as in the case of Gauß, this method is wrongly attributed to him. He mentions the method in the third edition of one of his most seminal works, the first two of which he did not mention the method at all [7].

..................Content has been hidden....................

You can't read the all page of ebook, please click here login for view all page.
Reset