Flow of fluids By Dr Ahmed Mostafa Assist

Flow of fluids By Dr. Ahmed Mostafa Assist. Prof. Of Anesthesia & I. C. U

Flow of fluids Definition of flow: It is the quantity (Q) of fluid passing across a point in unit time (t). F=Q/t Flow of fluid may occur through: A. A tube of constant (uniform) diameter. B. A tube of variable (non-uniform) diameter. C. An orifice.

Flow of fluids - Flow is produced, in both gases and liquids, by the application of a pressure gradient. - Liquids and gases both fill the shape of their container. - The flow behavior of gases and liquids is still largely determined by density and viscosity, although gases have much lower density and viscosity than liquids.

Flow through a tube of constant diameter Laminar flow - Describes the situation when any fluid passes smoothly and steadily along a given path. - The flow is silent. - The resistance is lower. - The flow of fluid varies directly with pressure difference and inversely with the resistance

Flow through a tube of constant diameter Laminar flow - The column of fluid undergoing laminar flow appears parabolic (concentric) (The flow is greatest at the center and reach zero in the layer touching the sides of the tubes).

Flow through a tube of constant diameter Laminar flow - Flow velocity below the critical velocity. Velocity–pressure drop curve, showing transition between laminar and turbulent flow

Flow through a tube of constant diameter Laminar flow

Flow through a tube of constant diameter •

Flow through a tube of constant diameter Laminar flow Clinical applications: - To increase the rate of infusion of intravenous fluids. - Resistance to breathing is much greater when a tracheal tube of small diameter

Flow through a tube of constant diameter Turbulent flow - It occurs when a flow passes through a smooth uniform tube with a constriction, an orifice, a sharp bend, or some other irregularity. - The flow is noisy. - The resistance is higher. - Flow velocity above the critical velocity.

Flow through a tube of constant diameter •

Flow through a tube of constant diameter •

Flow through a tube of constant diameter Turbulent flow Clinical application: - During bronchial asthma. - During anesthesia: Avoid the angle piece connector and making the internal surface of the breathing surface smooth.

Flow through a tube of variable diameter The Bernoulli principle: When a fluid pass through a constriction in a tube an increase in the flow velocity of will be accompanied by a simultaneous reduction in its pressure. Explanation: There are two types of energy when fluid passes through a tube: 1 - Potential energy. 2 - Kinetic energy. Both are constant

Flow through a tube of variable diameter The Venturi effect: