Streamlines & turbulence a2 level-level-revision, physics, force-motion, drag-terminal-velocity, streamlines-turbulence - revision world
•
1 like•374 views
This document discusses streamlines and turbulence in air flow over stationary objects. It explains that in a wind tunnel, air moves over stationary objects like car bodies to model their movement through air. At low speeds, the air flow is laminar or streamlined, moving in layers with little resistance. As speed increases, the flow changes from laminar to turbulent at a critical velocity, causing much more drag. Turbulent flow is disordered and irregular, with drag depending on air density rather than viscosity.
Streamlines & turbulence a2 level-level-revision, physics, force-motion, drag-terminal-velocity, streamlines-turbulence - revision world
- 1. 10/6/13 Streamlines & Turbulence | a2-level-level-revision, physics, force-motion, drag-terminal-velocity, streamlines-turbulence | Revision World revisionworld.co.uk/a2-level-level-revision/physics/force-motion/drag-terminal-velocity/streamlines-turbulence 1/4 Search: Quick revise Home » AS & A2 LEVEL (A-Level) Revision » Physics » Force & Motion » Drag & Terminal Velocity » Streamlines & Turbulence Streamlines & Turbulence To be as fuel-efficient as possible, a car, train or aircraft needs to be designed to minimise the resistive forces acting on it. To investigate the resistive or drag forces due to movement through the air, a car body is placed in a wind tunnel. Here the car body is held stationary and the air moves around it; vapour trails show the air flow over the car body. The diagram below shows the air flow at a low speed over a car body. The flow is said to be laminar or streamlined. In a wind tunnel the air moves over a stationary object such as a car body to model the movement of the car through the air. This is a valid model, as it is the relative speed of the air and the object that determines the pattern of flow. In laminar flow: the air moves in layers, with the layer of air next to the car body being stationary and the velocity of the layers increasing away from the car body particles passing the same point do so at the same velocity, so the flow is regular the drag force is caused by the resistance of the air to layers sliding past each other Username or e-mail * Password * Not a member? To access free revision resources & create your revision timetable register here. Forgotten your password? Login Create a RW account with FaceBook GCSE REVISION AS & A2 LEVEL MY TIMETABLE UNI & JOBS STUDY HELP GAMES & COMPS
- 2. 10/6/13 Streamlines & Turbulence | a2-level-level-revision, physics, force-motion, drag-terminal-velocity, streamlines-turbulence | Revision World revisionworld.co.uk/a2-level-level-revision/physics/force-motion/drag-terminal-velocity/streamlines-turbulence 2/4 more viscous air has a greater resistance to relative motion and exerts a bigger drag force the drag force is proportional to the speed of the car relative to the air. Viscosity is a measure of the resistance of a fluid to flowing. Syrup and tar are viscous fluids; hydrogen has a very low viscosity. As the speed of the air passing over the car body is increased, the flow pattern changes from laminar to turbulent. This is shown in the diagram above. The changeover from laminar flow to turbulent occurs at a speed known as the critical velocity. Turbulent flow causes much more drag than laminar flow. In turbulent flow: the air flow is disordered and irregular the drag force depends on the density of the air and not the viscosity the drag force is proportional to the (speed)2 of the car relative to the air. Related resources Terminal Velocity QUESTIONS 0 1 0google 293 0delicious
- 3. 10/6/13 Streamlines & Turbulence | a2-level-level-revision, physics, force-motion, drag-terminal-velocity, streamlines-turbulence | Revision World revisionworld.co.uk/a2-level-level-revision/physics/force-motion/drag-terminal-velocity/streamlines-turbulence 3/4 Like Be the first of your friends to like this. Recent Activity Flight (Doris Lessing) | gcse-revision, english, short-stories, flight-doris-lessing | Revision... Be the first of your friends to recommend this. Migration | a2-level-level-revision, geography, population, migration | Revision World Be the first of your friends to recommend this. Flexibility Training | gcse-revision, pe-physical-education, training-methods-programmes,... Be the first of your friends to recommend this. Growing Up (Joyce Cary) | gcse-revision, english, short-stories, growing-joyce-cary | Revision World Be the first of your friends to recommend this. Setting and Atmosphere | a2-level-level-revision, english, prose, setting-and-atmosphere |... Be the first of your friends to recommend this. Facebook social plugin Recent Study Help requests & Student Jungle postings Movie News from the STUDENT JUNGLE Jack Ryan: Shadow Recruit administrator Movie News from the STUDENT JUNGLE Jackass presents: Bad Grandpa administrator Movie News from the STUDENT JUNGLE
- 4. 10/6/13 Streamlines & Turbulence | a2-level-level-revision, physics, force-motion, drag-terminal-velocity, streamlines-turbulence | Revision World revisionworld.co.uk/a2-level-level-revision/physics/force-motion/drag-terminal-velocity/streamlines-turbulence 4/4 Free Birds administrator Movie News from the STUDENT JUNGLE Hunger Games Catching Fire - Tickets and Trailer administrator UNIVERSITY/ COLLEGE New UCAS e-card launched administrator Home About us Advertise Contact Links Privacy Safety Sponsorship Teachers Terms Work for us