Introduction
When a viscous fluid flows along a fixed impermeable wall, or past the rigid surface of an immersed body, an essential condition is that a velocity at any point on the wall or other fixed surface is zero. To the extent to which the condition modifies the general character of the flow is dependent on the viscosity of the fluid. If a body has a streamlined shape and the fluid flowing over the body has a small viscosity that is not negligible, the modifying effect appears to be confined to the narrowest regions adjacent to the solid surfaces; these are called boundary layers. Within these layers, there is a rapid change in velocity which gives rise to a large velocity gradient normal to the boundary which produces a shear stress [1]. At the boundary layer where the flow of fluid at the surface of the body is where the shearing stress is not zero. However, outside the boundary layer there are negligible stresses therefore the fluid velocity increases further away for the wall or boundary [2].
The objective is to investigate the velocity profile and boundary layer in the test section of the UJ low-speed wind tunnel as well as to calculate the boundary layer thickness using Blausius, parabolic and cubic velocity profile assumptions as well as to compare results to with theoretical Navier-Stokes velocity profiles.
Literature Review
Low-speed Circulating wind tunnels
Wind tunnels can be divided into three categories according to the range of air speed. In the low air speed section of the wind tunnel where air speeds range from (0.1 – 1.5) m/s, has a test section with large cross-sectional area, is adopted to generate a low-speed environment for calibration of anemometers [3]. Occasionally, the low-speed wind tunnel contains ...
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...ayer to a turbulent boundary layer happens at some critical Reynolds number (Rex) in the order of 2 x 105 to 3 x 106 [6]. This depends on the on the roughness of the surface and the amount of turbulence there is downstream of the fluid flow. The critical location or distance along the plate xcr, comes closer to the leading edge of the plate as the free-stream velocity increases [6].
The purpose of the boundary layer is to all the fluid to change its velocity from the upstream value of U to zero on the surface [6]. Therefore, V=0 at y=0 and V=UÎ at the edge of the boundary layer with the velocity profile of u=u(x,y), bridging the boundary layer thickness [6]. This boundary layer characteristic is true for a variety of different flow situations [6].
Figure 6: Boundary layer thickness (a) standard boundary layer thickness, boundary layer displacement thickness [6].
3. Identify the layers of the Earth shown in the diagram to the right. (S6E5a)
They just forgot to mention the other effects of fluids in nature. “The influence of the fluid on a body moving through it depends not only on the body’s velocity but also on the velocity of the fluid,” this is called relative velocity ( ). The relative velocity of a body in a fluid has an effect on the magnitude of the acting forces. For example, as a long distance runner is running into a head wind, the force of the fluid is very strong. If the runner is running with the help of a tail wind, the current’s force is reduced and may even be unnoticeable.
"As a rule of thumb R< ~2000 laminar flow and R> ~3000 turbulent flow" Anything in between 2000 and 3000 is unstable and may go back and forth between laminar and turbulent flow.
We must first begin the today’s lab by connecting the thermometer that digitally detects surrounding temperature to the Lab Pro Interface located on the computer via...
In classical fluid dynamics, the Navier-Stokes equations for incompressible viscous fluids and its special (limiting) case the Euler equations for inviscid fluids are sets of non-linear partial differential equations that describes the spatiotemporal evolution of a fluid (gas). Both equations are derived from conservative principles and they model the behavior of some macroscopic variables namely: mass density, velocity and temperature.
Introduction to Aerodynamics Aerodynamics is the study of the motion of fluids in the gas state and bodies in motion relative to the fluid/air. In other words, the study of aerodynamics is the study of fluid dynamics specifically relating to air or the gas state of matter. When an object travels through fluid/air there are two types of flow characteristics that happen, laminar and turbulent. Laminar flow is a smooth, steady flow over a smooth surface and it has little disturbance. Intuition would lead to the belief that this type of air flow would be desirable.
chamber used as a control will be used to measure any changes due to air
As the air flows over the wing producing lift, it grabs onto the wings surface and causes drag. Drag can be measured by the equation D=Cd 1/2 (pV2)S, much like the lift equation. The drag coeficent Cd is found, again, by determining ...
In 1986, the National Renewable Energy Laboratories developed a wind resource assessment for the U.S. Department of Energy. The assessment consisted of surface wind data and upper-air data. The results of this project help today’s developers determine the best location for a wind farm, as shown in the map below.
When the Reynolds number is less than 10 .... it is considered laminar, when it is greater than 100 it is considered turbulent. The areas in between are defined as transitional and can go either way.
This chart shows the relationship between the fanning friction factor and the Reynolds number over a wide range of flow rates, from which the roughness parameter (e/D) for the piping system can be estimated.
On a more scientific note I am interested in mechanics of fluids. This interest was enforced last year when I had the opportunity to attend a lecture on fluid mechanics at P&G. At the conference I greatly expanded my knowledge regarding the physical aspect of fluids and their properties. In last year's AS course we have met a topic in this field. I will be applying ideas and knowledge gathered from last year for this investigation.
In this experiment, we attempt to make a musical instrument. My group decided to make a wind instrument, which is an instrument that requires a player to blow in it, in order to have sound. There are some examples of wind instrument like, trumpet, oboe, tuba, etc... In this experiment, we’re going to explain how our wind instrument was made, and how the instrument changes in frequency by blowing in it. For the materials, we used the straw to become our mouthpiece, and with a washing machine pipe to make the sound better, and to become the tube of our instrument. We will test different lengths of the instrument, and measure any difference in frequency, or pitch, between the lengths.
The barometer is a device for measuring the total pressure of the atmosphere. A primitive barometer can easily be constructed by taking a glass tube about a meter long, sealing one end, filling the tube completely with mercury, placing your thumb firmly over the open end, and carefully inverting the tube into an open dish filled with mercury. The mercury will fall to a height independent of the diameter of the tube and a vacuum will be created above it.