Related Experiment Video
Updated: Jul 27, 2026

11:59
High-speed Particle Image Velocimetry Near Surfaces
Published on: June 24, 2013
33.9K
Reply to Badger and Volker: Correctly estimating wind resources at large scales requires more than simple
1John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138; lmiller@seas.harvard.edu.
Abstract
No abstract available in PubMed .
Related Concept Videos
Maxwell-Boltzmann Distribution: Problem Solving
Individual molecules in a gas move in random directions, but a gas containing numerous molecules has a predictable distribution of molecular speeds, which is known as the Maxwell-Boltzmann distribution, f(v).
This distribution function f(v) is defined by saying that the expected number N (v1,v2) of particles with speeds between v1 and v2 is given by
This distribution function f(v) is defined by saying that the expected number N (v1,v2) of particles with speeds between v1 and v2 is given by
Estimation of the Physical Quantities
On many occasions, physicists, other scientists, and engineers need to make estimates of a particular quantity. These are sometimes referred to as guesstimates, order-of-magnitude approximations, back-of-the-envelope calculations, or Fermi calculations. The physicist Enrico Fermi was famous for his ability to estimate various kinds of data with surprising precision. Estimating does not mean guessing a number or a formula at random. Instead, estimation means using prior experience and sound...
Wind Turbine Machine Models
In the growing field of wind energy, incorporating wind turbine models into transient stability analysis is essential. Induction and synchronous machines are the primary models used, with induction machines being prevalent due to their simplicity and reliability.
Induction machines interact through the rotating magnetic field generated by the stator and the rotor. The key parameter is slip, which is the difference between synchronous speed and rotor speed relative to synchronous speed. Slip is...
Induction machines interact through the rotating magnetic field generated by the stator and the rotor. The key parameter is slip, which is the difference between synchronous speed and rotor speed relative to synchronous speed. Slip is...
Design Example: Calculating Safe Diameter for Wind-Exposed Disc
Assessing safety in wind-exposed installations is crucial to preventing potential failures. This example explores the calculation and design adjustments needed to mount a circular disc on a building facade, where wind forces are a primary concern. A 4-meter diameter disc was initially designed as an aesthetic feature facing winds at a velocity of 25 meters per second, with an air density of 1.25 kilograms per cubic meter. Given these conditions, the drag force on the disc was determined using...
Vectors in 2D: Problem Solving
A plane traveling due north at 180 km/h in still air was found to be 80 km off-course after 30 minutes, deviating approximately 5 degrees east of north. This deviation means the influence of a crosswind alters the plane’s intended trajectory. The actual ground path formed a diagonal, suggesting that the aircraft’s effective ground speed was reduced to 160 km/h and directed slightly to the east due to the wind.By analyzing the displacement from the intended path, the velocity contributed by the...
Introduction to Vector Fields
Vector fields provide a mathematical framework for describing quantities that possess both magnitude and direction at every point in space. Physical phenomena such as wind flow, ocean currents, magnetic forces, and fluid motion can all be represented using vector fields. In meteorology, for example, wind may vary continuously across a geographic region, with both speed and direction changing from one location to another. To visualize this behavior on a two-dimensional map, arrows are placed at...

