UNLABELLED With the capability to improve indoor air quality while simultaneously reducing energy demand, displacement ventilation is becoming popular. However, the numerical simulation of air distribution in an indoor space with displacement ventilation using computational fluid dynamics (CFD) is challenging because of the complexity of air diffuser geometry and the complicated airflow pattern...

OBJECTIVES To visualize the velocity gradients and the vorticities of physiological unsteady nasal flow using the computational fluid dynamics method and to compare the inspiratory phase and expiratory phase flow patterns. DESIGN An anatomically correct 3-dimensional nasal and pharyngeal cavity was constructed from computed tomographic images of a healthy adult nose and pharynx. The unsteady ...

We examined oronasal flow partitioning in 27 volunteers with normal or slightly increased nasal resistance (mean +/- SD, 0.24 +/- 0.19 kPa/l/s). Mean percentage of inspiratory nasal flow contribution was measured during spontaneous oronasal breathing. The averaged nasal admixture of airflow differed considerably within and between all subjects (mean +/- SD, 20.9% +/- 16.5%; range 1%-70%), showi...

OBJECTIVES To assess the Pre-bronchodilator criteria and the Post-bronchodilator criteria of FEV1/FVC ratio in diagnosing Airflow obstruction. METHODS An observational study was conducted from 1988 to 2006 at the Aga Khan University Hospital Patients referred to the pulmonary function test laboratory for spirometry with bronchodilator reversibility at the hospital during the above said period...

This paper considers factors that play a significant role in determining inspiratory pressure and energy losses in the human trachea. Previous characterisations of pathological geometry changes have focussed on relating airway constriction and subsequent pressure loss, however many pathologies that affect the trachea cause deviation, increased curvature, constriction or a combination of these. ...

Using optics combined with automatic control and computer real-time image detection technology, a novel noninvasive method of noncontact pressure manometry was developed based on the airflow and laser detection technology in this study. The new esophageal venous pressure measurement system was tested in-vitro experiments. A stable and adjustable pulse stream was produced from a self-developed p...

Asthma is a chronic respiratory disease characterised by fluctuating respiratory symptoms and reversible airflow obstruction.1,2 Confirmation of the diagnosis hinges on demonstrating airflow obstruction varying over time. Patients with undiagnosed asthma who consult repeatedly with symptoms ranging in severity3 may demonstrate perfectly normal spirometry. As there is no single ‘gold standard’ t...

A uniform pollutant concentration in indoor environments can be an inappropriate representation of breathing concentration. This is especially true when local airflow in the vicinity of an occupant is dominant in transporting pollutants. The present study investigates the airflow in the vicinity of a human body, effects of respiration on breathing concentration of particulate and gaseous pollut...

Airflow-induced bronchoconstriction (AIB) in mammals can be broadly categorized as either vagal-dependent or vagal-independent. Among mammals, rabbits and cats belong to the former and guinea-pigs belong to the latter categories. Although insufficient data are available to classify monkeys, dogs and man appear to occupy the middle ground in which a small but significant parasympathetic componen...