Investigation of reattachment length for a turbulent flow over a backward facing step for different step angle

Singh, A. P.; Paul, Akshoy Ranjan; Ranjan, Pritanshu

doi:10.4314/ijest.v3i2.68135

Cited by 9 publications

(1 citation statement)

References 3 publications

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“…The orifice discharge coefficient is a function of the Reynolds number and β [23]. The variable h is the length of the orifice plate between diameters D and d. The chemical sensors were placed at least 8 times the value of h away from the orifice plate to ensure that exhaled breath would flow over the chemical sensors [24]. In the device, the parameter values were: D = 28 mm, d = 14 mm, h = 7 mm, and P1, P2, A, B, and C indicate the location of pressure sensors, NO sensor, CO sensor, and O 2 sensor, respectively ( Fig.…”

Section: ) Flow Chamber Specificationsmentioning

confidence: 99%

Personal Lung Function Monitoring Devices for Asthma Patients

Kwan

Fung

Jansen³

et al. 2015

IEEE Sensors J.

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Asthma affects over 300 million people worldwide. Asthmatics experience difficulty breathing and airflow obstruction caused by inflammation and constriction of the airways. Home monitoring of lung function is the preferred course of action to give physicians and asthma patients a chance to control the disease jointly. Thus, it is important to develop accurate and efficient asthma monitoring devices that are easy for patients to use.While classic spirometry is currently the best way to capture a complete picture of airflow obstruction and lung function, the machines are bulky and generally require supervision. Portable peak flow meters are available but are inconvenient to use. There also exist no portable inexpensive exhaled breath biomarker devices commercially available to simultaneously measure concentrations of multiple chemical biomarkers.We have created a user-friendly, accurate, and portable external mobile device accessory that collects spirometry, peak expiratory flow (PEF), exhaled nitric oxide (NO), carbon monoxide (CO), and oxygen (O 2 ) concentration information from patients after two breath maneuvers. We have also developed a software application that records and stores the gathered test information and e-mails the results to a physician. Telemetric capabilities help physicians track asthma symptoms and lung function over time, which allows physicians the opportunity to make appropriate changes in a patient's medication regimen more quickly.

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Section: ) Flow Chamber Specificationsmentioning

confidence: 99%

Personal Lung Function Monitoring Devices for Asthma Patients

Kwan

Fung

Jansen³

et al. 2015

IEEE Sensors J.

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Analysis of reattachment length dynamics in cavities

Vilkinis

Pedišius

2020

Experimental Thermal and Fluid Science

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Higher-order moments with turbulent length-scales and anisotropy associated with flow over dune shapes in tidal environment

Sarkar

Mazumder

2018

Physics of Fluids

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The purpose of this research paper is to investigate the third-order moments of velocity fluctuations, turbulent kinetic energy (TKE) fluxes, turbulence dissipation rate, turbulent length scales, and Reynolds stress anisotropy in the wake regions over two artificial upstream-facing bed forms. For the structure having a smaller flow-facing slope (slanting forward-facing structure, named as SFFS), the maximum flow intermittency is 0.6% with a maximum flow reversal frequency of 0.24 Hz, whereas for the greater flow-facing sloped structure (vertical forward-facing structure, named as VFFS), up to 70% flow intermittency is noticed just downstream of the corresponding crest location with a maximum of 28 Hz flow reversal frequency. A strong negative M30 (stream-wise flux of stream-wise normal stress) and a strong positive M03 (vertical flux of vertical normal stress), implying the occurrence of ejection events, take place above the flow separation region along the generated shear layer. However, near the lee-surface, positive M30 and negative M03 imply the presence of sweep events. For both the cases, maximum of normalized TKE (κ) is generated in the vicinity of crest location, which spread over the retarding flow region near-bed of the trough and wake-flow region downstream of the crest. The production of turbulence is mainly concentrated at the interface of intense ejection and sweep dominated zones over the trough region for the VFFS case, and for the other bed form, i.e., SFFS case, maximum turbulence production is concentrated at the near-bed crest location. Near the bed, the length-scale of eddies in the inertial sub-range decreases substantially compared to that in the upstream. It is seen that in the region of negative kinetic energy production, local maximum anisotropy is found, especially for b11,22,33S and b11,22,33V components. Interestingly, at the corresponding crest points for SFFS and VFFS, maximum affinity toward the one-component isotropy is measured almost throughout the vertical height. However, a clear increasing trend in the affinity to a better isotropy; i.e., the three-dimensional isotropy is identified as the vertical height increases up to z ≈ 3 cm above the bed when a fair downstream location for the VFFS case is considered. A special look toward the investigation of possible connection of the flow region with negative TKE production with the stream anisotropy shows that a substantial increase in the degree of anisotropy (Ad) in the anisotropy invariant maps of the negative TKE production takes place for both the cases, when compared to that for the positive TKE production region.

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Investigation of reattachment length for a turbulent flow over a backward facing step for different step angle

Cited by 9 publications

References 3 publications

Personal Lung Function Monitoring Devices for Asthma Patients

Personal Lung Function Monitoring Devices for Asthma Patients

Analysis of reattachment length dynamics in cavities

Higher-order moments with turbulent length-scales and anisotropy associated with flow over dune shapes in tidal environment

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