1. Based on N-S equation for incompressible flow, Hint 1. du, Derive the s-equation (i.e. equation for & = v 4 multiply the equation by subtracting the equation for at axk 2 " ax, N +Uk You can try the following procedure. Obtain an equation for mean N-S equation by time averaging Obtain an equation for velocity fluctuation u, by subtracting the mean equation 3 Differentiate the equation for fluctuation with respect to x, du, x; rearrange and taking time average 6 multiply 5 by 2v Note: The above procedure is not only possible way to derive the s-equation. You can also try a different way. Differentiate the N-S equation with respect to x, first. Then, multiply du, au, ax ax identical result. 2 ) 1 op d'u ax +V 2 px, and taking time average. This way will also yields the