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Questions tagged [drag]

26 questions
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Below what Froude number can I neglect wave-making resistance on a vessel?

I want to do some very simplified drag calculations on a vessel. My hope was that calculating the skin-friction resistance would be enough to get a good estimate of the surge resistance. Because wave-making resistance is very speed dependent, I…
Mika Sundland
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How would adding a wind deflector in front of roof-mounted solar panels affect drag on an RV?

I am mounting solar panels on top of a recreational vehicle (RV). To reduce drag, I was planning on building a small ramp in front of the panels to deflect wind before it hits the flat panel and mounts. Here is a rough sketch (red is brackets, black…
Cade
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How does the pressurized suspension of the Hyperloop not affect the tube pressure?

So one of the proposed suspension systems that will be used on the hyperloop include the externally pressurized air cushions. These cushions lift (or at least help lift) the capsule and reduce drag when the capsule is in motion. Also, the tube…
TheMagicalMachine
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What is the area when calculating the drag coefficient for a race car wing?

The drag coefficient is given by the following expression $$C_d = \frac{2F_d}{\rho v^2 A}$$ For a race car wing (which is simply an airplane wing upside down to generate downforce), what should we consider as the area? The cross-sectional area…
user1790813
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Does the aerodynamic force qualify as a viscous damping force in the Mechanical Harmonic Oscillator

When reading about a harmonic oscillator, the most common form of damping is proportional to the velocity. $$F_D = c \;\dot{x}$$ Without giving much thought to viscous damping, one example I always thought of is the following. Taking my hand…
NMech
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Is the drag coefficient/velocity of of a vehicle based on frontal area?

Does the frontal area of a vehicle determine the velocity/drag coefficient of a car? A Ferrari 458 has a Cd of 0.33 while a Corvette C6 has a Cd of 0.29. Does this mean the Corvette will have less frontal area and more speed while the Ferrari should…
Aero15BitGO
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Does more downforce affect the acceleration and top speed?

How can downforce make a race car faster, apart from being faster around corners? I just recently learned that downforce can help a car accelerate from 0-60 mph faster. Usually, I thought drag didn't have a great effect on a car's 0-60 time. I also…
user34865
1
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1 answer

Does the terminal velocity of a sphere in free drop increase with increasing diameter?

I was trying today to calculate the terminal velocity of a hailstones with increasing diameter and mass. I was trying to figure out if larger hailstones will have a higher impact velocity or lower. I performed the calculation (I was a bit surprised…
NMech
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Required power to spin fan at certain RPM

I have a flat piece of wood shaped like this: And it is turning around axle. What i would like to know is, if it is rotated e.g. at 1000 RPM, how much power would that take? I know that drag force should be equal to…
samo ja
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How can i calculate drag on an Angled area?

I want to calculate drag force at special angle on a sphere . There are some grooves on the sphere and these groove have a special angle on the sphere. In other words, I want to calculate drag force on the these grooves. How can I do it in Fluent?
user19061
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Could car waste heat be used to lower drag?

If the waste heat was moved to areas of lower pressure such behind the car-green area- Could this reduce the drag from these areas of lower pressure. From what I understand this hot air would increase pressure in those areas but equally hot air is…
PhysicsPhun
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Anomaly in viscous force - vs - velocity relationships

It is well known that the viscous force (or drag force) is directionally proportional to the square of the velocity in many cases. For example the torque on motors driving a fan-type load (pump) is proportional (approximately) to the square of the…
Transistor Overlord
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Boat Hull Drag in Shallow Water

I paddle several different types of small craft in the ocean and bays near my home. One phenomenon I've observed is beyond my understanding of drag on a narrow displacement hull. When paddling in water less than maybe 6 feet in depth, there is a…
PJNoes
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Wooden Sailing Ships - Why The Drag Pieces of Common Logs Were Shaped like Sections of a Circle?

I was reading the website What is the difference between a nautical mile and a knot?, and it said The common log was a rope with knots at regular intervals, attached to a piece of wood shaped like a slice of pie. Mariners would lower the wood piece…
MeltedStatementRecognizing
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Drag force and coefficient for cylinder through water

Pushing a cylinder through the water with an angular velocity of $\omega$. The cylinder diameter and length are $D$ and $L$ respectively and the length from the rotation point to the center of the cylinder is $L_{arm}$. $F_D = \frac{1}{2} \cdot…
Babar
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