It is desired to obtain the discharge flow Q of a tank of section A, which contains a liquid of density and viscosity initially up to a height HO, through a horizontal conduit that leaves the bottom of the tank, with a circular section with a diameter D PA and of length L D (see Fig.), assuming that the viscous forces are dominant in the movement of the liquid in the duct. Give the validity criteria of this assumption and comment on the limits of validity of the expression Q(t) obtained. www A H(t) D L Q(t)