Dhyn Paulo B. Andrada
BS Biology 3rd year
Activity 3: Fluid Dynamics in Biology Learning Module
1. Differentiate fluid statics and fluid dynamics.
Fluid Statics and Fluid Dynamics form the two constituents of Fluid Mechanics. Fluid
Statics deals with fluids at rest while Fluid Dynamics studies fluids in motion.
2.
Describe laminar flow, continuous flow, viscous flow, transient flow & compressible
flow. What fluid dynamics equation applies to each.
laminar flow, also called streamline flow, type of fluid (gas or liquid) flow in which the fluid
travels smoothly or in regular paths. By the principle of conservation of mass, continuous
flow occurs when at any time, the discharge Q at every section of the stream is the same.
Viscous flows occur when the effects of fluid viscosity are balanced by those arising from
fluid inertia, body forces, and/or pressure gradients. Transient flow, is flow where the flow
velocity and pressure are changing with time. Compressible flow is the area of fluid
mechanics that deals with fluids in which the fluid density varies significantly in response
to a change in pressure.
3.
Is air a type of fluid? What type of flow applies to biological system? Describe fluids &
flow mechanisms in biological system.
Air acts like a fluid in that it moves and flows. A fluid is anything that flows. It is a substance
that has no fixed shape and changes in response to external pressures. Fluids include
liquids, gases, and plasma.
4.
How do Temp & Pressure affect mass flow rate? What specific equation describes it.
Mass flow is equivalent to the actual flow rate multiplied by the density. M = Q x ρ, where
Q is the actual flow and ρ is the density. As the pressure and temperature change, the
volume and density change, however the mass remains the same
5. What is the effect of resistance coefficient to the flow rate?
low resistance coefficient are dependent on the kind of fluid media, flow frequency, flow
rate and porosity, etc.
6. What are the different types of pressures involves in fluid mechanics? Explain how the
blood pressure is measured & its effect to blood flow.
The different kinds of pressure are: Absolute Pressure. Gauge Pressure. Vacuum
Pressure. First, a cuff is placed around your arm and inflated with a pump until the
circulation is cut off. A small valve slowly deflates the cuff, and the doctor measuring blood
pressure uses a stethoscope, placed over your arm, to listen for the sound of blood pulsing
through the arteries
7. How the different pressures unit pascals, psi, newton per square meter, mmHg, torr &
atmospheric pressure are related, derived & applied? Describe why mmHg unit is most
appropriate unit in blood pressure measurement.
pascal (Pa), unit of pressure and stress in the metre-kilogram-second system
(the International System of Units [SI]). Pounds per square inch (PSI) is a measurement
of pressure in the Imperial system of measurement. PSI is commonly used to measure
the pressure of gasses (pneumatic pressure) or liquids (hydraulic pressure).
Newtons/Square Meter is a unit that shows how the pascal unit is derived from other SI
units. Pressure is defined as Force/Area and the SI unit for Force is newtons (N) and the
SI unit for Area is Sq Meters (m²). 1 newton per square metre equals 1 pascal. The
abbreviation mm Hg means millimeters of mercury. Mercury was used in the first accurate
pressure gauges and is still used in medicine today as the standard unit of measurement
for pressure. The torr (symbol: Torr) is a non-SI unit of pressure defined as 1/760 of an
atmosphere. It was named after Evangelista Torricelli. The air around you has weight, and
it presses against everything it touches. That pressure is called atmospheric pressure, or
air pressure. It is the force exerted on a surface by the air above it as gravity pulls it to
Earth. As mercury is so much denser than water or blood, even very elevated blood
pressures result in it rising no more than about a foot. This quirk of medical history gives
us the modern measurement unit for blood pressure: millimetres of mercury.
8. What is Law of the wall, Hagen–Poiseuille law, Poiseuille law and Pascal's law?
The law of the wall (also known as the logarithmic law of the wall) states that the average
velocity of a turbulent flow at a certain point is proportional to the logarithm of the distance
from that point to the "wall", or the boundary of the fluid region.
The Hagen–Poiseuille equation describes the relationship between pressure, fluidic
resistance and flow rate, analogous to voltage, resistance, and current, respectively, in
Ohm's law for electrical circuits (V = R I ). Both electrical resistance and fluidic resistance
are proportional to the length of the device.
Poiseuille law is the law that the velocity of a liquid flowing through a capillary is directly
proportional to the pressure of the liquid and the fourth power of the radius of the capillary
and is inversely proportional to the viscosity of the liquid and the length of the capillary.
Pascal's law states that when there is an increase in pressure at any point in a confined
fluid, there is an equal increase at every other point in the container.