Water flows in a \( 3.0-\mathrm{cm} \)-diameter tube having a relative roughness of 0.002 with a constant wall temperature of \( 80^{\circ} \mathrm{C} \). If the water enters at \( 20^{\circ} \mathrm{C} \), estimate the convection coefficient for a Reynolds number of \( 10^{5} \). (Ans. \( 14878 \mathrm{~W} / \mathrm{m}^{2} \mathrm{C} \) )