Laminar Boundary-Layer Theory

A potential advantage of the physical approach to boundary-layer theory is that it forces an emphasis on the underlying physical description of the flow. However, unlike the asymptotic approach presented here, the physically derived theory provides no obvious means to improve the solution beyond the first level of approximation. Provided that the physical picture underlying the analysis is properly emphasized, the asymptotic approach can incorporate the principal positive aspect of the earlier theories within a rational framework for systematic improvement of the approximation scheme. 

---

Laminar boundary layer theory assumes that a uniform flow (V = constant) approaches a flat plate. A laminar flow region develops near the plate where the thickness of the laminar boundary layer increases with thickness along the plate, as developed in Example 4.2. If we assign 5 to be the boundary layer thickness, or the distance from the plate where the velocity is equal to 0.99 times the velocity that approached the plate, and 5c to be the concentration boundary layer thickness, then we can see that both 5 and 5c are functions of distance, x, from the leading edge, as shown in Figure 8.11. 

M7. Meksyn, D., New Methods in Laminar Boundary Layer Theory. Pergamon, New York, 1961. 

Laminar Boundary Layer Theory - The Integral Method... 

B model parameter in logarithmic velocity profile (—) b constant of integration in laminar boundary layer theory (—)... 

Figure 3.2 DifFuMOTi of point particles (R 0) to single cylinders placed normal to an air How. The theoretical curve for low Reynolds numbers is in good agreement with experimental data for diiifusion in aqueous solution (Dobry and Finn, 1956). The curve for high Reynolds numbers is based on data for heal transfer to air (Schlichting, 1979, p. 311) corrected by dividing the Nus.selt number by (it/This is equivalent to assuming that laminar boundary layer theory is applicable.

---