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The paper deals with a CFD based study of the transverse permeability of a textile woven structure. The reported numerical investigation is preconditioned by both previous experimental and CFD study on jet systems. It is also based on detailed experimental investigation of the porous structure of single layer woven fabrics, made of staple fiber yarns. The flow in through-thickness direction of the woven structures is presented as jet systems, issuing from set of orifices. Two different types of jet system (3×3 jets and 5×5 jets) with two types of jet cross sections (square and circular), corresponding to two different woven structures, are simulated. An analysis is made in terms of the structure of the woven fabrics (area and shape of the interstices between the threads), the parameters of the flow passing through the textile (velocity profiles and velocity fields through isosurfaces), the role of the type of the jet systems, representing the flow and the influence of the shape of the interstices between the threads on the flow pattern. It was found that the applied approach could be effectively used for studying of the transverse permeability of the woven fabrics.

The paper presents computational fluid dynamics-based numerical simulation of the through-thickness air permeability of woven structures, applying the theory of jet systems. The flow through the interstices between the warp and weft threads is modeled as an ''in-corridor''-ordered jet system, formed by nine jets, issuing from nine pores of the woven structure. Fifteen cases were simulated and three different turbulence models were applied in the simulation: k-", k-! and Reynolds stress model. The five simulated woven structures were manufactured and their air permeability was measured experimentally. The performed validation of the numerical results with the experimental values of the air permeability showed very good correlation with the experimental results. The analysis and the verification showed that the method can be applied for further investigation not only of the woven fabrics' air permeability, but also for investigation of the flow after a textile barrier of a woven type.

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People are the main reason for the deterioration of indoor air quality (IAQ) due to the continuous physiological metabolism processes in their bodies, including respiration. We present results from an investigation of the influence of indoor air temperature on the concentration of exhaled carbon dioxide (CO2). The investigation was preconditioned by previous findings on the effect of air temperature on human metabolism. However, our literature survey showed a lack of studies on the influence of the indoor air temperature on the exhaled CO2 (or metabolic CO2), which leads to the novelty of our results. Our experiments had two phases: measurement in a university classroom with an installed heating, ventilation, and air-conditioning (HVAC) system during regular classes and measurement in a specially designed small climate chamber, where the time variations of the CO2 concentrations, together with some physiological parameters, were measured. Two indoor air temperatures were set: 23 °C and 27 °C. The results obtained and their respective analyses show the strong effect of the two air temperatures on the CO2 concentration due to exhalation. In the classroom, the CO2 concentration at 27 °C was higher by 6.2% than at 23 °C. In the climate chamber, the CO2 concentration at 27 °C was higher by 9.6% than at 23 °C. Physiological parameters (oxygen saturation pressure, pulse rate, end-tidal CO2, and respiration rate) and their dependence on the air temperature were also measured in the climate chamber, establishing an effect of the temperature on the pulse rate.

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Purpose – The purpose of the paper is to simulate the effect of clothing insulation and activity on the interaction between the human body and the environment. Design/methodology/approach – A thermo-physiological model, integrated into a Fluent CFD software package is applied. The temperature of the skin surface, clothing surface and heat flux (dry and total heat flux) through layers of clothing with different insulation level are numerically investigated in function of the clothing insulation and the different activities performed indoors. Findings – The increase of the clothing insulation leads to increase of both skin and clothing temperature. Higher temperature difference ΔT between the room temperature and skin temperature provokes more dynamic change of the skin temperature and decreases the thermal comfort of the person. The increase of the metabolic rate, however, leads to more uniform skin temperature, regardless the temperature difference ΔT. With the increase of the clothing insulation for a constant metabolic rate the total heat flux remains constant, but the dry heat flux decreases, while the evaporative heat flux increases. Originality/value – The joint influence of clothing insulation and indoor activities on the thermal interaction between the body and the environment is assesses using a thermo-physiological model, integrated in a CFD software package.