question_answer

Using the Prandtl's mixing length concept, how is the turbulent shear stress expressed?

A) \[\rho l\,\overline{\frac{du}{dy}}\]                      

B) \[\rho {{l}^{2}}\,\overline{\frac{du}{dy}}\]

C) \[\rho l\,{{\left( \overline{\frac{du}{dy}} \right)}^{2}}\]               

D) \[\rho {{l}^{2}}\,{{\left( \overline{\frac{du}{dy}} \right)}^{2}}\]