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Fluid Dynamics

The study of the motion of fluids (liquids and gases) and the forces causing this motion, Fluid Dynamics has several subdisciplines, including hydrodynamics and aerodynamics. To ask and answer questions about Fluid dynamics and its subdisciplines, come on in to the Fluid Dynamics category.

621 Questions

What size is a water wheel?

The size of a water wheel can vary widely depending on its design and purpose, ranging from small wheels that are just a few feet in diameter to large industrial wheels that can exceed 20 feet in diameter. Typically, smaller water wheels are used in residential or small-scale applications, while larger wheels are used in mills or hydroelectric plants. The wheel's size is often determined by the volume of water flow available and the intended mechanical power output.

Why does a car sink in the ocean?

A car sinks in the ocean primarily due to its weight and density being greater than that of water. When a car is submerged, it displaces water, but the buoyant force acting on it is not enough to counteract its weight, leading it to sink. Additionally, if water enters the car, it increases the overall weight and reduces buoyancy further, hastening the sinking process.

Where do you get water beads?

Water beads can be found at craft stores, garden centers, and online retailers like Amazon. They are often used for floral arrangements, sensory play, or decoration. You can also find them in stores that specialize in home and garden supplies. Be sure to check the product description to ensure they are safe for your intended use.

What type of lever is a toothbrush when in use?

A toothbrush acts as a third-class lever when in use. In this configuration, the effort is applied between the fulcrum (the point where the brush touches the teeth or gums) and the load (the resistance of the plaque and food particles on the teeth). This arrangement allows for a greater range of motion and speed at the brush head, making it effective for cleaning.

What kinds of shapes do water balloons come in?

Water balloons typically come in a variety of shapes, with the most common being round or oval, resembling small, elastic spheres. Some may also have slightly elongated or tapered forms, especially when filled. Additionally, there are novelty water balloons that can be found in fun shapes like animals or characters, often used for themed events or parties. Overall, while the classic shape is round, creativity in design allows for various playful forms.

How does air flow around a wing of a plane create lift?

Airflow around a wing generates lift primarily through the principles of Bernoulli's principle and Newton's third law of motion. As air moves over and under the wing, the wing's shape—typically curved on top and flatter on the bottom—causes air to travel faster over the top surface, creating lower pressure. Meanwhile, the higher pressure beneath the wing pushes it upward. This difference in pressure results in the upward force known as lift, allowing the plane to rise and stay aloft.

What is a boundary layer What causes a boundary layer to develop?

A boundary layer is a thin region adjacent to a surface where the effects of viscosity are significant, leading to velocity gradients in fluid flow. It develops due to the interaction between the fluid and the surface, causing the fluid's velocity to decrease from its free-stream value to zero at the surface due to friction. Factors such as surface roughness, flow speed, and fluid properties influence the thickness and behavior of the boundary layer. This phenomenon is crucial in various fields, including aerodynamics and hydrodynamics, as it affects drag and heat transfer.

What energy is transferred as a golf club does work on a golf ball?

When a golf club strikes a golf ball, kinetic energy from the club is transferred to the ball. This energy transfer propels the ball forward, converting the club's motion into the ball's motion. Additionally, some energy may be converted into sound and heat due to friction during the impact. Overall, the primary energy transferred is kinetic energy.

What type of ammo do you shoot in your World War 2 walther model pp 7.65?

The World War II Walther Model PP typically uses 7.65mm Browning ammunition, also known as .32 ACP (Automatic Colt Pistol). This cartridge was widely used in various European handguns during that era. When selecting ammunition, it's essential to choose high-quality, factory-loaded rounds to ensure reliable performance and safety. Always check the firearm's manual or consult with a knowledgeable gunsmith if you're unsure about the appropriate ammunition.

How much pressure is needed to create limestone?

Limestone is primarily formed from the accumulation of calcium carbonate (CaCO3) through biological processes and sedimentation, rather than from high pressure. However, geological processes that contribute to the formation of limestone can involve pressures of around 3000 to 5000 psi (pounds per square inch) over millions of years, which can cause the compaction and cementation of sediments. This pressure is typically associated with the burial of sediments over time rather than a direct requirement for limestone formation.

What is complex potential in fluid dynamics?

In fluid dynamics, complex potential is a mathematical concept that combines both potential flow theory and irrotational flow theory. It allows for the representation of fluid flow in two dimensions using complex numbers, where the real part corresponds to the velocity potential and the imaginary part to the stream function. This approach simplifies the analysis of flow around bodies and helps in understanding fluid behavior.

Why are airplains and birds have stremlined?

Birds are streamlined because all species of birds that ever existed and were

NOT streamlined were unable to outfly the streamlined predators, so they got

caught and eaten, laid very few eggs, had very few hatchlings, and became

extinct.

Airplanes are streamlined because that design reduces aerodynamic drag,

which directly subtracts from thrust. So a streamlined airplane uses much

less fuel than a square airplane does to cover the same distance. Once this

fact became generally known, nobody would buy any square airplanes, and

the companies that built them went out of business. A lot like the birds.

How can one Calculate the PSI of water in river based off velocity of the river?

To calculate the PSI of water in a river based on the velocity of the river, you can use the formula PSI = 0.433 * (velocity in feet per second)^2. This formula accounts for the pressure increase due to the velocity of the flowing water. Just plug in the velocity of the river in feet per second into the formula to calculate the PSI.

How can the accuracy of a venturimeter be increased?

Reduce errors by using a discharge coefficient to account for inaccuracies resulting from assuming plug flow and neglecting friction in the Bernoulli equation. Also ensure that the device is horizontal or replace the pressure term with "P + static head" if a horizontal device is not possible.

Source: Chemical Engineering Fluid Mechanics, Ron Darby, 2nd edition, pages 296 & 303.

Does a sonic boom occur only when passing the speed of sound?

No, the "sonic boom" is the noise observed as a supersonic shockwave generated by an object already traveling faster than the speed of sound passes over you. Different observers hear the same shockwave at different times, depending on their location relative to the supersonic object generating that shockwave.

What is the pressure inside an inverted hollow cylinder in water and how to calculate it?

The pressure inside an inverted hollow cylinder in water is equal to the pressure at the depth of the cylinder's centroid multiplied by the specific weight of water. To calculate it, use the formula: pressure = (specific weight of water) * (depth of centroid of cylinder).

How compressible is air?

Air is compressible because it is a gas and its molecules have space between them that can be reduced when pressure is applied. The compressibility of air can be described by its bulk modulus, which is a measure of its resistance to compression. At standard atmospheric conditions, air is relatively compressible compared to liquids and solids.

What is the shape of a drop of oil placed in the surface of water?

A drop of oil placed on the surface of water will typically form a near-perfect circle due to surface tension forces that minimize the surface area of the liquid.

What is the circulation pattern of hot and cold air?

Hot air rises because it is less dense, creating a convection current with cooler air sinking to replace it. This circulation pattern repeats as the cycle of warm air rising and cool air sinking creates a continuous flow. This movement of air is a key factor in regulating weather patterns and temperature distribution on Earth.

How does paint turn into a solid?

Most paints turn solid by simple evaporation of solvent from the mixture, leaving behind the pigment solids and a binder. A small number of paints partially turn solid by a polymerization reaction, these usually come in two separate components that you must mix before painting (similar to epoxy adhesives).

What is an example of ferromagnetic fluid?

Ferrofluid is an example of a ferromagnetic fluid. It is a liquid that becomes strongly magnetized in the presence of a magnetic field. Ferrofluids are often used in speakers, seals, and cooling systems.

What will happen if a sudden expansion is provided immediately after the throat of a venturimeter?

If a sudden expansion is provided immediately after the throat of a venturi meter, the flow velocity will decrease abruptly due to the sudden increase in cross-sectional area. This can lead to recirculation zones, pressure recovery losses, and inaccurate flow rate measurements due to disturbances in the flow profile. It is important to ensure a gradual and controlled expansion to maintain accurate measurements.

Why as the water falls its speed increases and the area of cross section decreases?

It is explained by mass conservation, and water being an incompressible fluid.

Imagine water going through a pipe with varying inside diameters Di's. Water will

flow the fastest in the pipe section with the smallest diameter, and will flow the

slowest in the widest section of the pipe.

The product of the volumetric average velocity of the water flow v, times the

cross section area A, is equal to the volumetric flow rate (vol/time) G.

G = v∙A

If you have a constant volumetric flow rate, if the area reduces to half, the velocity doubles.

By the way, if you multiply the volumetric flow rate G by the liquid density ρ, you

get the mass flow rate Q, (mass/time). Q = G∙ρ = ρ∙v∙A

Why the value of coefficient of contraction is greater then the theoratical value in experiment?

The coefficient of contraction in an experiment may be greater than the theoretical value due to factors such as flow imperfections, wall roughness, or turbulence in the flow. These factors can lead to additional energy losses and create a greater contraction in the flow compared to the ideal theoretical case. Experimental conditions and inaccuracies in measurements can also contribute to discrepancies between the observed and theoretical values of the coefficient of contraction.

Rate of flow against pressure gradient graphs?

The rate of flow against pressure gradient graph typically shows a linear relationship. As the pressure gradient increases, the rate of flow also increases proportionally. This is in accordance with Poiseuille's law, where flow is directly proportional to the pressure gradient and the fourth power of the radius of the vessel and inversely proportional to the viscosity of the fluid.