Effects of turbulence stimulators on the boundary layer and resistance of a ship model as detected by hot wires effectsofturbule00bres Year: 1950 15 the Pohlhausen type6 which are given by â â â¢-(â 12 + M y X/yf ik -X T 2\T) ' V 6 dU dU Hi) +' -)'(*) [3 being the velocity gradient, and 6 is the so-called Pohlhausen boundary layer where x â â IT ta' dx' Lower Critical Reynolds Number R,,*=420I , Data from experiments of Schubouer and Skramstad (from Reference 3) 400 800 1200 1600 Boundary Layer Reynolds Number ^ Figure 10 - Curve of Neutral Stability Calculated By Lin for Blas
Effects of turbulence stimulators on the boundary layer and resistance of a ship model as detected by hot wires effectsofturbule00bres Year: 1950 15 the Pohlhausen type6 which are given by â â â¢-(â 12 + M y X/yf ik -X T 2\T) ' V 6 dU dU Hi) +' -)'(*) [3 being the velocity gradient, and 6 is the so-called Pohlhausen boundary layer where x â â IT ta' dx' Lower Critical Reynolds Number R,,*=420I , Data from experiments of Schubouer and Skramstad (from Reference 3) 400 800 1200 1600 Boundary Layer Reynolds Number ^ Figure 10 - Curve of Neutral Stability Calculated By Lin for Blasius1 Plat Plate Plow (From Reference 4) The stability calculations for various X have produced the rela- tionship between lower critical Reyn- olds number and X, as shown in Figure 11. Here it may be seen that decreas- ing pressure (increasing velocity, X > 0) in the direction of flow are favorable to the stability of the lami- nar layer and that increasing pressures (X < 0) are unfavorable. It must be pointed out that the theory does not predict the po- sition of transition. The instabil- ities which may arise take time to amplify to the state at which they produce transition. Hence it may be expected that the transition Reyn- olds number is much greater than the -8 -6-4-2024 6 Karman - Pohlhausen Parameter X Figure 11 - Critical Values of R,* as a Function of the Velocity Gradient Parameter X (Computed by Schllchting and Ulrich, see Reference 5)
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