References
1. G.S. Beavers and D.D. Joseph, “Boundary Conditions at a Naturally Permeable Wall,” J. Fluid Mech., vol. 30, 1967.
2. P.G. Saffman, “On the Boundary Condition at the Surface of a Porous Medium,” Stud. Appl. Math., vol. 50, no. 2, pp. 93–101, 1971.