# Fluid Mechanics: Boundary Layer Thickness

For the laminar part of the boundary layer it is possible to calculate the boundary layer thickness using the Blasius Equations. The reason why you may want to know the thickness of the boundary layer is because outside of the boundary layer the fluid particles will not be effected by viscous forces. To calculate the boundary layer's thickness the following equation and table would be used.

(1)

δ = Boundary Layer Thickness

ν = Kinematic Viscosity

x = Length from the tip of the Edge

U = Fluid Velocity outside the boundary layer

u = Fluid Velocity inside the boundary layer at point of interest

### Blasius Solutions for Laminar Flow

η = y(U/υx)^{1/2} |
ƒ'(η) = u/U |
η |
ƒ'(η) |

0 |
0 |
3.6 |
0.9233 |

0.4 |
0.1328 |
4.0 |
0.9555 |

0.8 |
0.2647 |
4.4 |
0.9759 |

1.2 |
0.3938 |
4.8 |
0.9878 |

1.6 |
0.5168 |
5.0 |
0.9916 |

2.0 |
0.6298 |
5.2 |
0.9943 |

2.4 |
0.7290 |
5.6 |
0.9975 |

2.8 |
0.8115 |
6.0 |
0.9990 |

3.2 |
0.8761 |
∞ |
1.0000 |

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