Nature of Flow of a Liquid
Wilmer W Nichols, Michael F O'Rourke, Elazer R Edelman, Charalambos Vlachopoulos in McDonald's Blood Flow in Arteries, 2022
Blood velocity disturbances both in laboratory animals and in humans can be measured with a constant-temperature anemometer in association with hot-film sensors mounted on rigid L-shaped probes or at the tip of cardiac catheters (see Chapter 6). As blood flows past a heated sensor, it cools it, causing the electrical resistance to change (Ling et al., 1968; Seed and Wood, 1970; Clark, 1974). The voltage required to maintain a constant temperature is related to the blood flow velocity near the tip. Thus the anemometer system detects the velocity in the region of the sensor. Because of its high-frequency response, such a system is sensitive to the rapid and random fluctuations of velocity that occur in turbulence. Hot-film probes in water have measured fluctuations of velocity at frequencies as high as 1000 Hz (Clark, 1974; Walburn et al., 1980).
Fluid Dynamics of the Aortic Valve
Mano Thubrikar in The Aortic Valve, 2018
Stein et al. made measurements of the blood flow velocity in the ascending aorta of humans with a hot-film anemometer probe.20 A catheter-tip hot-film velocity probe along with constant temperature anemometer, which maintains the film temperature at 5°C above the ambient temperature, was used. First, the tip of a fluid-filled #8 French catheter was positioned near the aortic valve and a hot-film probe was passed through this catheter under X-ray. The velocity at the tip of the probe was measured while the probe was pulled back to various positions in the ascending aorta. As mentioned earlier, the velocity was obtained directly from the voltage variation required to keep the temperature of the probe constant.
Performing in cold environments
R. C. Richard Davison, Paul M. Smith, James Hopker, Michael J. Price, Florentina Hettinga, Garry Tew, Lindsay Bottoms in Sport and Exercise Physiology Testing Guidelines: Volume I – Sport Testing, 2022
The ambient environment should be measured adjacent to the participant. Wet bulb globe temperature (WBGT) includes measurement of convection (dry bulb temperature; Tdb), evaporation (wet bulb temperature; Tw) and radiation (globe temperature; Tg): In most laboratory scenarios, radiation is likely to be minimal and therefore Tdb and relative humidity (RH) will suffice. RH can be measured using a humidity meter or calculated from the difference between Tw and Tdb. If measuring wind speed, the anemometer should be positioned carefully, as the angle will influence the measurement.
Upper body sweat mapping provides evidence of relative sweat redistribution towards the periphery following hot-dry heat acclimation
Published in Temperature, 2019
Caroline J. Smith, George Havenith
Before commencing the acclimation regimen, the cycle ergometer was adjusted, and a level of resistance was established which could be maintained throughout the first exercise period, and that was sufficient to elicit a 1.4°C Tcore rise. Three 50cm diameter fans (JS Humidifiers plc, Littlehampton, UK) were mounted in a linear arrangement on a wooden frame, 1 meter in front of the bike. This enabled an equal distribution of wind over the height of the body, with an air velocity of 1.0 m.s−1. Daily calibration of air velocity was performed using a hot wire anemometer (model TSI Alnor 8455. TSI Instruments Ltd, UK. Range 0.125–50 ms-1.) at the position of the cycle ergometer seat. Tcore, Tsk, ambient temperature (Ta), relative humidity (rh) and HR were recorded at one min intervals, and manual readings recorded every five min. The HA regime was based on the Fox constant strain technique [27,28], involving intermittent exercise in 45°C and 20% rh (hot-dry) to achieve and maintain a 1.4°C elevation in Tcore above baseline. Participants completed a 90-min exposure involving three, 20 min bouts of submaximal cycling, interspersed with 10 min rest periods. Resistance was adjusted to achieve the desired increase in Tcore or at the request of the participant. If Tcore exceeded a 1.4°C increase from baseline or approached 39°C participants interrupted exercise and sat on the cycle ergometer to limit any further elevation, until Tcore started to drop.
The effect of cleaning and repainting on the ship drag penalty
Published in Biofouling, 2021
I. K. A. P. Utama, B. Nugroho, M. Yusuf, F. A. Prasetyo, M. L. Hakim, I. K Suastika, B. Ganapathisubramani, N. Hutchins, J. P. Monty
The flow measurements were performed using an in-house-built Melbourne University Constant Temperature Anemometer (MUCTA) system (see Perry 1982 and Perry and Morrison 1971 for MUCTA details). The hot-wire probe used is a single-normal hot-wire probe (Dantec type 55P05) that is connected to a 4mm diameter probe support (Dantec type 55H21). For the sensing element, a 5µm Platinum Wollaston wire is used, and to minimise attenuation due to end conduction it is etched with a length of 1mm, resulting in a length-to-diameter ratio 1987; Hutchins et al. 2009). Because measurements are conducted with the same hot-wire across a range of freestream velocities (to obtain various Reynolds number), the viscous scaled wire length 1987; Hutchins et al. 2009). The hot-wire is calibrated in situ in the freestream before and after each measurement. To minimise error due to hot-wire drift, a correction is conducted by periodically moving the hot-wire to the freestream which provides a single recalibration point that can be used to adjust the calibration (Talluru et al. 2014). The hot-wire probe is attached to a two-dimensional computer controlled traversing system, which permit measurements over a spanwise and wall-normal plane.
Wireless binaural hearing aid technology for telephone use and listening in wind noise
Published in International Journal of Audiology, 2019
Agnes Au, Jessica M. Blakeley, Richard C. Dowell, Gary Rance
Testing was conducted in a soundproof booth. Participants were positioned with the loudspeaker at 300 degrees azimuth clockwise and the fan at 60 degrees azimuth clockwise, relative to the front. This set up was chosen to maximise the effect of the Speech in Wind feature. A Bowens JetStream 250 Wind Machine was used to produce the airflow, which was measured with a Skywatch Xplorer 1 anemometer. At the highest setting, the wind speed was measured through the anemometer at 3 ± 0.5 m/s from the centre of the head at a distance of 1.5 m. The variation in airflow speed was due to the constant buffeting effect of the blades of the fan.
Related Knowledge Centers
- Ohm'S Law
- Laser Doppler Velocimetry
- Laser
- Ultrasound
- Infrared Gas Analyzer
- Pitot Tube