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Exam of Fluid Mechanics 20 July 2021 Exercise 1 (9 points) These two connected tanks contain fluids with specific weight 1 and 2. Along the vertical, the two fluids are separated by cylinders that can slide frictionless and have specific weight s. The cylinders are also hold by a wire passing over two pulleys. Finally there is a metallic manometer, and the system is in equilibrium as depicted. Knowing: everything except a, find: a. Exercise 2 (9 points) A fluid steadily flows in this system. The tank on the right ha s a finite size. The elevations of the free surfaces are as sketched (Z1<Z2). Knowing all the sketched quantities, the Gibson coefficient for the expanding reach and the outflow coefficient = Cc×Cv, find: the direction of Q1 e Q2; the quantities Z1, Q2, Qe, WP, . Sketch the lines for total head and pressure head Question 1 (6 points) Define the drag coefficient and explain how it depends on roughness for a blunt body Question 2 (6 points) Derive the expression of the tensor for Reynolds stresses ________________________________________________________________________________ A successful student will have at least 12 points in the exercises and at least 6 points in questions. n H h h a = ? D1 D2 1 2 s s P Z1 = ? Z2 Q1 Qe = ? Q2 = ? Ze, De WP = ?  = ? m D3 D1, 1 D2, 2 L1 L2 L3 L4 ,  P Traccia di soluzione Esercizio di statica Equilibrio del cilindro di sinistra sotto l’azione di: peso proprio, spinta da sopra, spinta da sotto, tensione del filo 𝛾 ଵሺ𝐻െ𝑎 ሻ𝜋𝐷ଵ ଶ 4 ൅𝛾௦ℎ 𝜋𝐷ଵ ଶ 4 ൅𝑇ൌ𝑛 𝜋𝐷ଵ ଶ 4 Equilibrio del cilindro di destra, sotto l’azione delle medesime forze 𝛾ଵ𝐻 𝜋𝐷ଶ ଶ 4 ൅𝛾௦ℎ 𝜋𝐷ଶ ଶ 4 ൅𝑇ൌ ሺ𝑛൅𝛾 ଶ𝑎ሻ𝜋𝐷ଶ ଶ 4 La distanza a si determina uguagliando le due T Esercizio di dinamica La Q2 va verso sinistra per la condizione Z1<Z2. La Q1 va verso destra…