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12.5 The Onset of Turbulence
The pressure difference is created by the two pumps in the heart.
Blood can reach individual cells and exchange substances, such as oxygen and waste products, with them.
The system can regulate flow to individual organs by varying vessel diameter.
The total cross-sectional area of the tubes through which the blood flows is increased by branching larger vessels into smaller vessels.
An arteries with a cross section may branch into 20 smaller arteries with a total of.
The resistance of the branchings is reduced so that pressure is not completely lost.
The average speed of the blood in the smaller vessels is reduced because of branching.
The blood flow in the aorta is 25 cm/s, while in the capillaries it is 1mm/s.
The blood can exchange substances with the cells in the capillaries and alveoli.
We can predict if the flow will be smooth or turbulent.
We know that flow in a very smooth tube or around a smooth object will be very slow.
At high speeds, even flow in a smooth tube or around a smooth object will experience turbulence.
At intermediate speeds, flow can be variable between turbulent and laminar.
Turbulence in the circulatory system can sometimes be detected with a stethoscope, such as when the upper arm's partially collapsed brachial arteries are measured.
The sounds at the start of blood flow are called Korotkoff sounds.
A stethoscope can sometimes be used to detect a ballooning of arteries.
Heart murmurs are sounds produced by turbulent flow around damaged and insufficiently closed heart valves.
In a similar way to a radar used to detect storms, a stethoscope can be used to detect turbulence.
In the large part of the blood vessel, flow is smooth and turbulent in the part that is narrowed by plaque.
The flow can be chaotic in the transition region.
A unitless quantity is the Reynolds number.
Experiments have shown that is related to turbulence.
The flow is called laminar.
The flow is turbulent for over 3000.
For values between 2000 and 3000, flow can be stable, but small obstructions and surface roughness can make it turbulent.
Most of the body has a quiet blood flow.
In the aorta, the speed of the blood flow rises above a critical value of 35 m/s and becomes turbulent.
We have all of the information we need, except the fluid speed, which can be calculated from.
The flow should be smooth since it is below 2000.
Over the last few decades, the topic of chaos has become quite popular.
When a system's behavior is so sensitive to a factor that it's hard to predict, it's chaotic.
The study of chaotic behavior is called the field of chaos.
The flow of a fluid with a Reynolds number between 2000 and 3000 is a good example of chaotic behavior.
It is not impossible to predict whether the flow is turbulent or not, but it is extremely sensitive to the nature of the flow.
A small variation in one factor can have a big effect on the flow.
Phenomena is chaotic and can be analyzed with similar techniques.
A moving object in a fluid stream is the same as a stationary object in a fluid stream.
The fluid around the moving object can be either turbulent or laminar.
It is possible to predict when a moving object creates turbulence.
The fluid density, the object's speed in the fluid, and the length of the object are characteristic of 12.55.
If the object has a smooth shape, flow around it can be laminar.
The transition to turbulent flow can take between 1 and 10.
Depending on the surface, there can be a wake behind the object.
Between 10 and, the flow can be either turbulent or laminar.
Even at the surface of the object, the flow is completely turbulent.
When the objects in the fluid are small, laminar flow occurs.
The Reynolds number is used to calculate the diameter of a ball.
Since all values in it are either given or found in tables of density and viscosity, we can use to calculate.
A turbulent wake is implied by this value.
Planes and sailboats create turbulence as they move.
The Bernoulli principle only gives results that are qualitatively-correct.
The force depends on the object's speed.
Experiments show that the drag is proportional to the speed of the flow.
drag behaves with greater complexity for greater than.
The object's size, speed, and fluid viscosity are all related to laminar flow around a sphere.
The larger the object, the more drag we expect.
There is a flow with less than 1.
There is a force to the left on the ball.
The net force to the left is greater than the net force to the right because fluid speed is less.
Drag goes up a lot.
If we neglect air resistance, an object falling through a fluid will not continue to accelerate indefinitely because of the increase in speed.
The object falls at a constant speed once this happens.
Sky divers falling through the air, particles of sand falling in the ocean, and cells falling in a centrifuge are all examples of this.
The drag on the object depends on the fluid and the size of the object.
The force depends on the density of the object.
For low-viscosity fluids and objects with high densities, terminal speed will be the best.
When a skydiver is in a pike position, they head first with their hands on their side and legs together.
By measuring the terminal speed of a slowly moving sphere in a fluid, one can find its viscosity.
It can be difficult to find small ball bearings around the house, but a small marble will do.
Drop the marble into the center of the fluid and watch it fall.
If the terminal speed is proportional to the viscosities, compare your values.
Estimating the rates of small particles can be done with knowledge of terminal speed.
From watching mud settle out of dirty water, we know that it is a slow process.
Centrifuges can be used to speed up the process by creating frames in which the terminal speed can be much greater.
Atomic and molecular transport phenomena are related to fluid motion.
At any temperature, atoms and Molecules are in motion.
They move about in fluids even if there is no flow.
Liquids, like odors or fish fumes, can diffuse through solid objects.
Diffusion is a process that takes a long time.
The densities of common materials make it impossible for molecules to travel very far before they collide.
The quantity is the constant for a particular molecule.
A random walk is a type of motion.
That gets smaller as the molecule gets bigger.
The average speed at a given temperature is related to the mass.
Oxygen in air is more abundant than in water.
The random walk of an oxygen molecule in water is slowed considerably.
Each molecule in water collides about once per second.
The average speed of the molecule increases with temperature.
The average energy of the molecule is related to the temperature.
The average time it takes for a molecule to move is 1.0 cm.
The expression for the average distance moved in time can be used to solve the problem.
The quantities are known.
We stir sugar into water because we want it to diffuse.
The most important effects of diffusion occur over small distances.
Most of the oxygen in the eye comes from the thin tear layer covering it.
If you place a drop of food coloring in a still glass of water, it will slowly diffuse into the surroundings until its concentration is the same everywhere.
There are no barriers that prevent free diffusion.
We can look at its direction and rate.
More molecules will move out of a high concentration area than into it because of random motion.
After the process is partially completed, the net rate of diffusion is higher.
The difference in concentration affects the net rate of movement.
Concentration difference affects the net rate of diffusion.
More molecules will leave a region of high concentration than will enter it from a region of low concentration.
There would be no net movement if the concentrations were the same.
The net rate of diffusion is proportional to the constant.
The more likely a molecule is to leave a high concentration, the farther it can diffuse.
The factors that affect the rate are hidden.
Values of are affected by temperature and cohesive forces.
The exchange of waste products between the blood and tissue and between air and blood in the lungs is called Diffusion.
As organisms became larger, they needed quicker methods of transportation because of the larger distances involved in the transport, leading to the development of circulatory systems.
Less sophisticated single-celled organisms still rely on diffusion for the removal of waste products.
Barriers that affect the rates of diffusion are some of the most interesting examples.
Water diffuses through your skin when you soak a swollen ankle.
Oxygen, carbon dioxide, and other substances move through the cells.
diffusion rates through the thin structures can be high.
The method of transport through Diffusion is important.
One type of semipermeable Membrane has small pores that allow only small Molecules to pass through.
In other types of membranes, themolecules can be dissolved in the membrane or react with it while moving across it.
Current research involves not only chemistry and physics, but also the subject of the Membrane function.
The water concentration drivesOsmosis.
Water is more concentrated in your body.
When you soak a swollen ankle, the water moves out of your body into the lowerconcentration region of the salt.
The blood is cleansed by the kidneys with the use of osmosis and dialysate.
A lot of pressure can be created by Osmosis.
If osmosis continues for some time, consider what will happen.
The solution to the right is caused by water moving from the left into the region on the right.
The movement will continue until the pressure on the right is large enough to stop further osmosis.
The back pressure is what this pressure is called.
Depending on the concentration difference, smoltic pressure can be large.
The osmotic pressure will be 25.9 atm if pure water and sea water are separated.
Turgor in plants is an example of pressure created by osmosis.
The fluid in a cell exerts a pressure against the wall of the plant.
The plant is supported by this pressure.
Pressures can be caused by Dialysis.
Since water is less concentrated there, Osmosis will be to the right.
On the right side, back pressure can be created.
Water can be desalinated by using reverse osmosis.
Any substance that won't pass through a given membrane can be removed with reverse dialysis.
Substances can pass in a different direction than we expect.
Cypress tree roots can be used to extract pure water from salt water.
There is no back pressure to cause this.
Water and other substances can be moved by active transport.
The kidneys use a lot of active transport to move substances into and out of blood.
At least 25% of the body's energy is spent on active transport of substances at the cellular level.
The study of active transport brings us into the realm of biology, biophysics, and biochemistry, and it is a fascinating application of the laws of nature to living structures.
The flow rate is defined to be the volume flowing past a point in time or where it is.
The liter is a common unit.
The cross-sectional area of the flow and its average are related to the flow rate and the power of the equation.
The third is power associated with height.
The sum on each side of fluid in layers that do not mix is stated in Bernoulli's equation.
It's due to the fact that the fluid is rubbing against each other.
Table 12.1 has representative values.
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