Drag Definition and 751 Threads

Hello I am preparing for my aerodynamics exam and I'm having trouble with this question. Why is the Reynolds number of the airflow over a wing important in determining the value of lift and dragThe Reynolds number is important for determining laminar and turbulent flows over a body. It is a...

Hi all, I´m a researcher in computational biology thinking on topics quite far from my field. Would you help me? Thanks in advance! I want to calculate the drag force in air of big rigid spherical and cylindrical objects at speeds form 0 to 100 Km/h. Their diameter would range from 1 to 20m...

Homework Statement From dimensional analysis it is found that the drag force F that a fluid (density ρ, viscosity μ) exerts on a sphere (diameter d) moving through a fluid at a velocity u is given by cD = f(Re), where . The table below gives the relationship between the drag...

Homework Statement Consider a flat plate moving at V = 105 ft/s in an atmosphere with P = 2100 psf and T = 75F, with a viscosity of vis = 3.7373e-7 slug/ft-s. The plate has a 2 foot chord and a 3.5 foot span. a. Find the drag on the plate for: i. A boundary layer that is laminar over the...

I was looking through a Taylor's Classical Mechanics chapter and I have a question about the derivation. So basically, it starts out with m\dot{v}_{y}=mg - bv_{y} and you find v_{ter} by letting m\dot{v}_{y}=0 where when you solve for v_{y} you will get v_{ter}. Now the book states how we...

Homework Statement A tennis player hit a serve of 251 km.h-1 in a match. Calculate the Drag Force acting on the tennis ball. Diameter of ball is 6.5cm, density of air is 1.3 kg.m-3 and air viscosity is 1.8x10-5 kg.m-1.s-1. Homework Equations Drag Force is: Fd= \pi.d2.CD.pf.u2.1/4...

This is probably a maths question which I am struggling with the question states that drag is proportional to the square of the velocity D = kv^2 And there is a linear relationship between the square of the velocity and the acceleration dv/dt = - 0.0154 v^2 + 0.402827 assume the mass of...

I am trying to figure out how much force i need to pull to drag an object with a given surface 1634 square inch and weight from a given depth. Between 100 - 200 m 11-21kg psi. However I do not know how to use Newtons laws correctly in this senario. The object does not the to accelerate. Can you...

Hi This isn't a homework question, just a problem I thought up of but would require some implementation I don't really know how to do. Homework Statement If I have a microfluidic channel with laminar flow and a parabolic velocity profile as predicted in the Hagen-Poiseuille flow, and I...

I'd like to know the right formula to calculate torque of a quadrotor propeller (propeller pitch is constant) due to aerodynamic drag in terms of angular velocity ω. For the sake of my simulation I'm assuming `APC 10x4,7` propellers. I'd like to refer to...

http://www.youtube.com/watch?v=_EU-raX_40Q&feature=relmfu This link demonstrates the modelling of projectile motion with drag. I was just wondering if anyone can help me find the downloadable link he mentions at 5:23

Homework Statement angled piece of sheet set at various distances to a set fan, the sheet is placed on scales and they measure the amount of force the wind creates. There are noticeable differences at the different distances and angles. Homework Equations wind force and wind pressure...

Heyy uh I have this problem I'm confused about; there is a body at rest (a sheet of cardboard set at an angle to electronic scales) and a fan blowing at the surface area. There is noticeable difference when I adjust the speed of the fan, the angle it sits at and the distance to the fan. Anyway I...

Homework Statement Hello guys, I am here and really need your help. In the figure below, the water flow from inlet and then out at outlet with velocity, v = 0.71 m/s. The objective is to calculate find the drag force and lift force act on fishing lure. I have done Ansys Fluent analysis but...

I was wondering, if the force that causes a car to move in one direction is matched by the drag force opposing in the other direction, why does the car move at a constant velocity rather than moving at zero velocity. I thought that when one force opposes the other equally, there is no net...

I am trying to predict the flight of an object with a parabolic trajectory including drag due to air resistance how do I do this? the wiki page was not clear its my understanding its relative to the square of the speed.

Hi All, Assuming Stokes drag, wikipedia suggests this problem (the solution for v(t) ) has an analytical solution. Is this right? http://en.wikipedia.org/wiki/Drag_%28physics%29#Very_low_Reynolds_numbers.E2.80.94Stokes.27_drag Could someone point me to the derivation online? Or a...

Alright, I am trying to work out some equations on a project to determine if fictional instances of physics are possible or not. In my case, I am seeing how a person travels if they are thrown from a jet that is traveling vertically (don't ask). I have completed the equations to solve how far...

Homework Statement An object is influenced by 2 forces: environmental force F1 = 42 tons and a hydrodynamic drag factor F2 = 200 kN. These forces are directed against each other (one attempting to 'weaken' the other one). The corresponding mass of object is 10,112 tonnes. I am trying to create...

The drag force can be affected by the velocity of the object relative to the fluid. Does that mean the wind affects the drag force, since it changes the velocity of air particles?

What wing area should a plane weighing 2000lbs have to enable it to land at a speed of 35mph? Max CL= 1.50 Formula for lift lb= CL*ρ*A*v^2/2 when i set up the problem i get this 2000= 1.50*ρ*A*(35)^2/2 and i realize I am trying to solve for A (area) but what does the ρ...

Homework Statement Any help would be appreciated, whether that is formulas or working out. Questions For each of the vertical levitation examples calculate the lift force exerted on the ball. For each of the inclined levitation examples calculate the lift and drag forces exerted on the ball...

Homework Statement I've been given the mission to find out the drag coefficient for the Ahmed Body. The drag coefficient itself it too hard to measure. The problem for me is to find a way to separate the drag coefficient to Pressure Drag coefficient and Skin friction coefficient. My question...

Relation b/w slip ratio and drag force...Race car Vehicle Dynamics help... hii guyz... this is the first time i am posting on this forum and hope i ll get help... I was going through Race car vehicle dynamics by milkins and found a relation given on pg 64 which says... Drag...

Myth Or Fact? -- Wind drag on flaming arrows In a stable atmosphere would arrows that have their head on fire accelerate faster than a regular arrow?

Hi there, I am working an a stationary, laminar flow model and would like to calculate the drag of that model. Now the Comsol forum guys suggest to use the operator reacf(u). It is also used in the "Flow over a circular cylinder" tutorial. Does anyone know where to get it from or how to use...

I am running ANSYS fluent simulation flow over naca 0012 airfoil. So far the lift coefficient is similar with the published papers. The problem is drag coefficient is different so much in term of value compared to published papers. I have check my mesh quality and boundary condition, it shows...

http://en.wikipedia.org/wiki/Drag_coefficient from wikipedia, it is written 1.98-2.05 for flat plate perpendicular to flow(2D) , but I have a differrent b/h ratio plate, where h=157mm and b=816mm , b/h=5.197 how to get the drag coefficient in this case? Thanks.

Hi, Can anyone help explaining the points of action of drag and thrust forces on an aeroplane in flight and also the realtionship between Lift-Drag ration and wing configuration?! Any help would be great!

I'm trying to model the flight of a small spherical object (such as a ping-pong ball) through air at smallish velocities (\approx 5{_{m/s}}) with linear drag so that F_{d}=-bv. The problem is, I can't find a table of linear drag coefficients (b) anywhere; it's always just the normal drag...

Hi I know what pressure and friction drag are, I am having a hard time trying to find out how can you calculate the coefficient of drag for them? I think i have came across an equation for it: F_{D} = .5*ρ*v^{2}*A*C_{D} where F_{D} is the force of drag, ρ is density, v is velocity, A is the...

Homework Statement An object moving in a liquid experiences a linear drag force: D =(bv, direction opposite the motion), where b is a constant called the drag coefficient. For a sphere of radius R, the drag constant can be computed as b = 6 pi n R, where n is the viscosity of the liquid...

Hi, An object is falling near the surface of the Earth. We assume there is a drag force acting on it due to the air molecules. It's initial conditions are such that it rotates and is in a chaotic motion. Will the object will fall in the end in such a way to minimize air drag? And if yes -...

The linear drag coefficient is a function only of object size and medium viscosity. Multiply sources say viscosity of air is independent of pressure and density. How can the linear drag be independent of density of the medium? It seems like less dense medium should mean fewer collision and in...

Hi I am a mechanical engineering student currently busy with my final year project on spoilers I need to design manufacture and test a device to test different spoilers it must determine the drag coefficient of the spoiler and the down force generated by the spoiler without the use of an...

The figure shows a graph of actual position-versus-time data for a particular type of drag racer known as a "funny car." Estimate the car's velocity at 2.0s Equation: v = m/s I thought I knew how to solve this, and I made a tangent line at the curve and 2s, and when I do the slope at...

i want the gear so the car is going 100 mph at 6000 rpm 1:1 drive at end of 1/4 mile. have figured out this much for dry run. 32 inch DIAMETER tire x pi 3.14 = circumference. let's call it 100 inches. one mile is 5280 feet. engine will turn at 6000 RPM. RPM is in minutes. MPH is in hours...

Homework Statement Consider a rocket is subject to linear resistive force, f = -bv . \dot m is constant. Use the equation: m \dot{v} = -\dot{m }v + f to determine the velocity of the rocket : since the rate of mass lost is constant let \dot{m} =k vex = nuzzle velocity v = \frac{k}{b}...

How can I design an experiment to find the drag coefficient of a cone without knowing the force of drag that is acting on the cone? Is this even possible?

I am trying to write a java program to simulate the motion of a projectile undergoing a drag proportional to the velocity squared, but i am having some issues writing the acceleration part. This is my attempt, not sure if its right though; a=g-kv^2 da/dt=-k dv^2/dt since dv^2/dt=2vdv/dt...

Simplified drag equation?? Hi, I am a 3D programmer and I am trying to apply drag to some of my objects in my software. After looking around and from previous research i know that calculating drag isn't such a simple thing to do and involves knowing air density, object area and the drag...

Hi guys, I have been trying to measure the drag characteristics of a wind tunnel model by using a pitot-static tube set up. From which the transducer will output to me the stream-wise velocity profile based on the pressure differential measured. Following which, in order to evaluate the...

Homework Statement Find work of drag force in term of proportional to Velocity (Like: Wd=kV^n ,when k=constant value n=Real number) Homework Equations (Fd=1/2*ρ*v^2*Cd*A) The Attempt at a Solution I've a problem with my science project. I try to find the terminal velocity of a...

Homework Statement A blimp of mass 110 kg is pulled at an angle of 52 degrees downwards with respect to the horizontal for D=7 km on level ground at a constant velocity v=14 m/s. If the coefficient of drag (K in F=Kv^2) is 0.5 kg/m, how much work is done by the person pulling? Homework...

Hey guys, I've been looking around online and only find formulae for car passing through a distance with an initial velocity but nothing to calculate the speed of an object starting from a stance and accelerating to complete a distance. I have a car that has done a 1/4 mile (375m) and...

Homework Statement Calculate the pressure drag cofficient for a cylinder using the trapezoidal and simpson's rule (assume the flow is the same on both sides of the cylinder). Angle (deg) Cp 0 1 30 0.274 60 -1.565 90...

If you have a falling object and wind in the horizontal direction, the object ends up falling to the ground at an angle. Why does the drag force only have a vertical component? Thanks!

Hello, everyone! Any ideas how to measure drag or drag coefficient on a body of simple shape? We should conduct an experiment without use of sophisticated equipment. Thank you!

Hi everyone, I am hoping that someone may be able to advise me on an issue i currently have. I am trying to implement a Physics computer simulation (only basic) designed for children learning about forces. One of the sub games that i have created is to fire a character from a cannon and find...

Hi ! First at all thanks for read, I'm new in the forum ... So the problem is, I would calculate the drag coeff of a car but in the coeff formula I would like to know which AREA is considered for this. drag coeff is given by = 2F / ρ(V^2) A Where : F is the drag force ρ is the mass...