Geodesic
Moving of surfaces method which preserves spherical parts
Matematičeskoe modelirovanie, Tome 2 (1990) no. 6, pp. 97-101 
A. S. Shvedov. Moving of surfaces method which preserves spherical parts. Matematičeskoe modelirovanie, Tome 2 (1990) no. 6, pp. 97-101. http://geodesic.mathdoc.fr/item/MM_1990_2_6_a9/
@article{MM_1990_2_6_a9,
     author = {A. S. Shvedov},
     title = {Moving of surfaces method which preserves spherical parts},
     journal = {Matemati\v{c}eskoe modelirovanie},
     pages = {97--101},
     year = {1990},
     volume = {2},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MM_1990_2_6_a9/}
}
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Voir la notice de l'article provenant de la source Math-Net.Ru

It is necessary to find the location of boundaries for every time when one is computing a nonsteady problem of mathematical physics with moving boundaries. The boundaries are surfaces if solution depends on three space variables. Assume that a plot of one boundary is a part of sphere and all points of this plot move with identical velocities when $t=0$. Then during some time the plot will be a part of sphere. In this paper an algorithm is suggested of moving surfaces preserving spherical plots under indicated conditions.