Friction velocity
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Dimensional analysis shows that at a wall a charateristic velocity, called the ''friction velocity'', <math>u_*</math>, can be defined in the following way: | Dimensional analysis shows that at a wall a charateristic velocity, called the ''friction velocity'', <math>u_*</math>, can be defined in the following way: | ||
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Where <math>\tau_w</math> is the [[Wall shear stress|wall shear stress]] and <math>\rho</math> is the fluid density at the wall. | Where <math>\tau_w</math> is the [[Wall shear stress|wall shear stress]] and <math>\rho</math> is the fluid density at the wall. | ||
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| + | The friction velocity can also be computed from the [https://en.wikipedia.org/wiki/Darcy%E2%80%93Weisbach_equation Darcy friction factor]: | ||
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| + | :<math>u_{\star} = U \cdot \sqrt{\frac{f}{8}}</math> | ||
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| + | Where <math>U</math> is the average velocity and <math>f</math> is the Darcy friction factor. | ||
Latest revision as of 23:46, 7 December 2024
Dimensional analysis shows that at a wall a charateristic velocity, called the friction velocity, 
, can be defined in the following way:
Where 
is the wall shear stress and 
is the fluid density at the wall.
The friction velocity can also be computed from the Darcy friction factor:
Where 
is the average velocity and 
is the Darcy friction factor.
