A thin region near a surface where viscosity matters.
Near a surface fluid velocity rises from zero (no-slip) to free stream within thickness δ. Laminar flat-plate δ≈5x/√Re_x; turbulent grows faster. Skin friction and heat transfer arise in this layer; transition and separation are important.
At 10 m/s over 1 m of plate in air, a laminar layer would be about 6 mm thick.
The boundary layer explains skin friction and separation, which are important for drag on aircraft, ships and pipes.
A thin region near a surface where viscosity matters.
The boundary layer explains skin friction and separation, which are important for drag on aircraft, ships and pipes.
It grows along the surface, and its thickness depends on the distance from the leading edge and the Reynolds number.
Turbulent layers have higher skin friction but are less likely to separate, while laminar layers have lower friction but separate more easily.
Typical applications include estimating the skin friction drag on an aircraft wing, explaining why a rough surface increases drag and locating where flow may separate on a turbine blade.
Study "Similitude and model testing" first (topic 69 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
Displacement and momentum thickness. Blasius solution. Wall shear stress.
At 10 m/s over 1 m of plate in air, a laminar layer would be about 6 mm thick.
The next topic is "Drag and lift", which builds directly on this one.
It is classed as Intermediate in Thermodynamics & Fluids (topic 70 of 105). It is an intermediate topic. Work through the beginner topics in Thermodynamics & Fluids first.
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